Fonts: use craft-fonts as an optional build input; move the Japanese fonts out

The Japanese fonts (BIZ UDPGothic Regular/Bold for the UI, BIZ UDMincho for text
watermarks; #110, #114) now come from storytold/craft-fonts instead of assets/fonts/.

- crates/engine/build.rs: the craft-fonts recipe. With CRAFT_FONTS_DIR set it embeds
  the manifest's fonts as lightcraft_engine::CRAFT_FONTS (wasm32: BIZ UDPGothic Regular
  only, for the web size budget); unset, CRAFT_FONTS is empty. Local files only, no
  network; craft-fonts is not in any Cargo.toml.
- UI: theme::font_definitions adds the Japanese faces after Inter and egui's defaults
  in every family (BIZ UDPGothic first, Bold first for semibold). About box lists the
  embedded families.
- Watermarks: Inter, then the craft-fonts Japanese faces (Mincho first).
- Removed BIZUDPGothic-Regular/Bold.ttf, BIZUDMincho-Regular.ttf and their OFL files,
  and their ATTRIBUTION rows; added an attribution row for craft-fonts as an optional
  build input; NOTICE updated.
- Tests: Japanese glyph tests use CRAFT_FONTS and skip without it; new tests for
  Japanese in the UI with craft-fonts and for the UI and watermarks without it.
- CI: the FreeBSD job builds/tests with craft-fonts. Releases check out craft-fonts at
  a pinned commit, build with CRAFT_FONTS_DIR + CRAFT_FONTS_REQUIRED=1, and ship the
  fonts' OFL licences (plus NOTICE) in every package.
- Docs: AGENTS.md, CLAUDE.md, README, docs/web.md, docs/localization-ja.md, ROADMAP,
  parity.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

AGENTS.md

@@ -62,10 +62,21 @@ of it. Full standard: `../craftrules/standards/never-crash.md`
 ## Assets: icons, images, fonts (ABSOLUTE RULE — never violate)
 - **Never use any iconography, image, artwork, font, sound or other asset from Adobe products** (no Lightroom/Creative Cloud icons, no screenshots, no presets/profiles/LUTs, no UI bitmaps — not even as a temporary placeholder or "reference copy"). Observing Adobe's UI to imitate *layout and behaviour* is allowed; copying or tracing its assets is not.
 - **This includes Adobe's open-licensed assets**: no Source Sans/Serif/Code or Source Han fonts, no Adobe Fonts, no
-  Adobe-published icon sets, sample photos, colour profiles or LUTs — even when OFL/MIT. The UI font is Inter (OFL).
+  Adobe-published icon sets, sample photos, colour profiles or LUTs — even when OFL/MIT. The UI font is Inter (OFL);
+  Japanese fonts come from craft-fonts (below).
 - Every asset in the repository must be one of: **our own original work** (e.g. icons drawn in code as vectors, procedurally generated demo photos), **public domain / CC0**, **Creative Commons** (CC-BY / CC-BY-SA with attribution honoured), **OFL** (fonts), or **permissive open-source** (MIT/Apache-2.0/BSD/ISC) — or contributed by a person who created the asset and licenses it openly.
 - **Exception: `docs/brand/`.** The ArtCraft name, wordmark and logos there are ArtCraft Team trademarks, not open source and not covered by LightCraft's MIT OR Apache-2.0 licence (`LICENSE-MIT`, `LICENSE-APACHE`, `NOTICE`); their terms are in `docs/brand/LICENSE-brand.txt`. Use them only unmodified and never redraw, recolour or derive from them.
 - **Every asset must have an entry in `assets/ATTRIBUTION.md`** (path, title, author/creator, source URL or "original work", licence, date added, modifications) and its licence text when required (e.g. `assets/fonts/OFL-*.txt`). Add the entry in the same commit as the asset. Assets without an attribution entry must not be committed.
+- **Fonts live in [storytold/craft-fonts](https://github.com/storytold/craft-fonts), never in this repo.** Don't commit
+  font files here (Inter, already in `assets/fonts/`, is the one exception); add new fonts to craft-fonts. LightCraft
+  uses it as the optional build input `CRAFT_FONTS_DIR`: `git clone https://github.com/storytold/craft-fonts ../craft-fonts`
+  then `CRAFT_FONTS_DIR=../craft-fonts cargo run -p lightcraft` (or any cargo/xtask command). `crates/engine/build.rs`
+  embeds the manifest's fonts as `lightcraft_engine::CRAFT_FONTS` (wasm32: BIZ UDPGothic Regular only); the UI
+  (`theme::font_definitions`) and the export watermark renderer use its Japanese faces as fallbacks after Inter. Unset,
+  `CRAFT_FONTS` is empty: everything builds, tests and runs, but Japanese text has no glyphs. Releases always build
+  with it (`release.yml`, `CRAFT_FONTS_REQUIRED=1`) and ship the fonts' OFL licences. Tests that need these fonts skip
+  without it; the FreeBSD CI job runs them with it. Rules: craftrules
+  [`standards/fonts.md`](https://github.com/storytold/craftrules/blob/main/standards/fonts.md).
 - Icons drawn in code (e.g. `crates/ui-egui/src/icons.rs`) are original work and are recorded in `assets/ATTRIBUTION.md` as such; do not trace them from Adobe icons.
 - Demo/test images: generated procedurally by `lightcraft-scenes`, or CC0 downloads kept in the gitignored `corpus/` with their source recorded. Screenshots of Adobe apps live only in the gitignored `plan/` and are never committed or published.
 - **Enforced:** `cargo xtask assets` (in `ci`) fails when an image/icon/font/sound/video/raw/ICC/XMP file is not matched