feat: initial Münster Haushalt icicle viewer

Editorial single-page viewer for the City of Münster's 2026/2027
budget draft, built as an Astro v6 SPA with a 4-level zoomable
icicle (Produktbereich → Produktgruppe → Category → Breakdown).

Highlights:
- Multi-flow data layer over the official open-data CSVs
  (Aufwendungen + Erträge, 2008–2028) with overlap reconciliation
  across plan years.
- Year slider as a 21-year mini-histogram of both flows;
  drag-to-scrub and click-to-jump, with bars morphing via CSS
  transitions on SVG geometry attributes.
- Vertically centred icicle with year-outline rectangles framing
  each year's relative budget size, à la Bostock's animated treemap.
- Headline "ausgibt / einnimmt" toggle; sidebar Aufwendungen/Erträge
  rows double as flow toggles. Active flow in Aufwendungen-purple /
  Erträge-orange (OKLCH).
- Click-to-zoom via path-keyed lookup with ZOOM_COL_BOUNDS that
  reallocate the depth axis per zoom state. Zoomed item moves to the
  sidebar; canvas shows its descendants only (no adjacent-block leaks).
- Sidebar shows path-specific Aufwendungen/Erträge/Saldo plus the
  source-PDF Beschreibung; Erläuterungen behind a collapsed details.
- Build-time PDF extraction (scripts/extract-pg-sections.mjs) parses
  68 Produktgruppen' Beschreibung + Erläuterungen sections from
  Band 1, including 10 cells of structured Mio.-€ breakdowns
  (Steuern, Transferaufwendungen, etc.) that drive the level-4 view.
- URL state sync for path, year, and flow via history.replaceState
  so any zoom is shareable.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

fonts/OFL.txt

@@ -0,0 +1,93 @@
+Copyright 2022 The Figtree Project Authors (https://github.com/erikdkennedy/figtree)
+
+This Font Software is licensed under the SIL Open Font License, Version 1.1.
+This license is copied below, and is also available with a FAQ at:
+https://openfontlicense.org
+
+
+-----------------------------------------------------------
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+-----------------------------------------------------------
+
+PREAMBLE
+The goals of the Open Font License (OFL) are to stimulate worldwide
+development of collaborative font projects, to support the font creation
+efforts of academic and linguistic communities, and to provide a free and
+open framework in which fonts may be shared and improved in partnership
+with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
+redistributed freely as long as they are not sold by themselves. The
+fonts, including any derivative works, can be bundled, embedded, 
+redistributed and/or sold with any software provided that any reserved
+names are not used by derivative works. The fonts and derivatives,
+however, cannot be released under any other type of license. The
+requirement for fonts to remain under this license does not apply
+to any document created using the fonts or their derivatives.
+
+DEFINITIONS
+"Font Software" refers to the set of files released by the Copyright
+Holder(s) under this license and clearly marked as such. This may
+include source files, build scripts and documentation.
+
+"Reserved Font Name" refers to any names specified as such after the
+copyright statement(s).
+
+"Original Version" refers to the collection of Font Software components as
+distributed by the Copyright Holder(s).
+
+"Modified Version" refers to any derivative made by adding to, deleting,
+or substituting -- in part or in whole -- any of the components of the
+Original Version, by changing formats or by porting the Font Software to a
+new environment.
+
+"Author" refers to any designer, engineer, programmer, technical
+writer or other person who contributed to the Font Software.
+
+PERMISSION & CONDITIONS
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of the Font Software, to use, study, copy, merge, embed, modify,
+redistribute, and sell modified and unmodified copies of the Font
+Software, subject to the following conditions:
+
+1) Neither the Font Software nor any of its individual components,
+in Original or Modified Versions, may be sold by itself.
+
+2) Original or Modified Versions of the Font Software may be bundled,
+redistributed and/or sold with any software, provided that each copy
+contains the above copyright notice and this license. These can be
+included either as stand-alone text files, human-readable headers or
+in the appropriate machine-readable metadata fields within text or
+binary files as long as those fields can be easily viewed by the user.
+
+3) No Modified Version of the Font Software may use the Reserved Font
+Name(s) unless explicit written permission is granted by the corresponding
+Copyright Holder. This restriction only applies to the primary font name as
+presented to the users.
+
+4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
+Software shall not be used to promote, endorse or advertise any
+Modified Version, except to acknowledge the contribution(s) of the
+Copyright Holder(s) and the Author(s) or with their explicit written
+permission.
+
+5) The Font Software, modified or unmodified, in part or in whole,
+must be distributed entirely under this license, and must not be
+distributed under any other license. The requirement for fonts to
+remain under this license does not apply to any document created
+using the Font Software.
+
+TERMINATION
+This license becomes null and void if any of the above conditions are
+not met.
+
+DISCLAIMER
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
+OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
+DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
+OTHER DEALINGS IN THE FONT SOFTWARE.

fonts/README.txt

@@ -0,0 +1,77 @@
+Figtree Variable Font
+=====================
+
+This download contains Figtree as both variable fonts and static fonts.
+
+Figtree is a variable font with this axis:
+  wght
+
+This means all the styles are contained in these files:
+  Figtree/Figtree-VariableFont_wght.ttf
+  Figtree/Figtree-Italic-VariableFont_wght.ttf
+
+If your app fully supports variable fonts, you can now pick intermediate styles
+that aren’t available as static fonts. Not all apps support variable fonts, and
+in those cases you can use the static font files for Figtree:
+  Figtree/static/Figtree-Light.ttf
+  Figtree/static/Figtree-Regular.ttf
+  Figtree/static/Figtree-Medium.ttf
+  Figtree/static/Figtree-SemiBold.ttf
+  Figtree/static/Figtree-Bold.ttf
+  Figtree/static/Figtree-ExtraBold.ttf
+  Figtree/static/Figtree-Black.ttf
+  Figtree/static/Figtree-LightItalic.ttf
+  Figtree/static/Figtree-Italic.ttf
+  Figtree/static/Figtree-MediumItalic.ttf
+  Figtree/static/Figtree-SemiBoldItalic.ttf
+  Figtree/static/Figtree-BoldItalic.ttf
+  Figtree/static/Figtree-ExtraBoldItalic.ttf
+  Figtree/static/Figtree-BlackItalic.ttf
+
+Get started
+-----------
+
+1. Install the font files you want to use
+
+2. Use your app's font picker to view the font family and all the
+available styles
+
+Learn more about variable fonts
+-------------------------------
+
+  https://developers.google.com/web/fundamentals/design-and-ux/typography/variable-fonts
+  https://variablefonts.typenetwork.com
+  https://medium.com/variable-fonts
+
+In desktop apps
+
+  https://theblog.adobe.com/can-variable-fonts-illustrator-cc
+  https://helpx.adobe.com/nz/photoshop/using/fonts.html#variable_fonts
+
+Online
+
+  https://developers.google.com/fonts/docs/getting_started
+  https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Fonts/Variable_Fonts_Guide
+  https://developer.microsoft.com/en-us/microsoft-edge/testdrive/demos/variable-fonts
+
+Installing fonts
+
+  MacOS: https://support.apple.com/en-us/HT201749
+  Linux: https://www.google.com/search?q=how+to+install+a+font+on+gnu%2Blinux
+  Windows: https://support.microsoft.com/en-us/help/314960/how-to-install-or-remove-a-font-in-windows
+
+Android Apps
+
+  https://developers.google.com/fonts/docs/android
+  https://developer.android.com/guide/topics/ui/look-and-feel/downloadable-fonts
+
+License
+-------
+Please read the full license text (OFL.txt) to understand the permissions,
+restrictions and requirements for usage, redistribution, and modification.
+
+You can use them in your products & projects – print or digital,
+commercial or otherwise.
+
+This isn't legal advice, please consider consulting a lawyer and see the full
+license for all details.