feat(viewer): present subtitles, fonts, PNG + text in the PAK browser

Decode and present four more PAK item types in the pack browser's detail
pane. All content is decoded off-thread in build_pak_rows and attached to
each PakRow, then rendered with egui's own texture facilities — the Bevy
texture pipeline and egui's global font system are untouched.

formats crate (Bevy-free, reusable by CLI):
- ixud: parse IXUD localized-string tables as subtitle cue lists (UTF-16BE
  pool, SUBTITLE header + (text, timecode) pairs -> Vec<Cue{start,end,text}>).
- font: OTF/TTF/ttcf metadata (family / faces / glyphs) via ttf-parser.

viewer:
- PakRow gains `content: PakContent` (Subtitle | Font | Png | Text | None);
  classify_content fills it for IXUD / fonts / PNG / xml+text within the
  existing decode budget. Font samples are pre-rasterized off-thread with
  ab_glyph into an image (ImageRgba) — ab_glyph returns Option/Result at every
  step, so a bad font yields no sample instead of panicking (the earlier
  egui set_fonts approach crashed the app on atlas rebuild).
- draw_pak_browser dispatches on content: subtitle cue table, font metadata +
  sample image, PNG image, scrollable text; else the existing IDXD detail.
  Borrow-split PakView instead of cloning the (now heavy) rows each frame;
  one hash-keyed egui texture cache serves both PNG and font-sample images.

Subtitle<->movie auto-matching is deferred: movie filenames don't hash to the
IXUD keys and no cross-reference table was found (the link is an internal
MSG_DEMO id), so the movie player gets no subtitle track yet.

Tests: ixud unit tests; disc tests for the real English subtitle track
(cues + timecodes), eng/deu localization, font metadata, and off-thread
rasterization of the real font.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Cargo.lock

@@ -3760,7 +3760,7 @@ version = "0.25.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "36820e9051aca1014ddc75770aab4d68bc1e9e632f0f5627c4086bc216fb583b"
 dependencies = [
- "ttf-parser",
+ "ttf-parser 0.25.1",
 ]
 
 [[package]]
@@ -4592,6 +4592,7 @@ dependencies = [
  "thiserror 2.0.18",
  "tokio",
  "tracing",
+ "ttf-parser 0.24.1",
  "xdvdfs",
 ]
 
@@ -4599,9 +4600,11 @@ dependencies = [
 name = "sylpheed-viewer"
 version = "0.1.0"
 dependencies = [
+ "ab_glyph",
  "bevy",
  "bevy_egui",
  "futures",
+ "image",
  "rfd",
  "rodio",
  "sylpheed-formats",
@@ -5007,6 +5010,12 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "ttf-parser"
+version = "0.24.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5be21190ff5d38e8b4a2d3b6a3ae57f612cc39c96e83cedeaf7abc338a8bac4a"
+
 [[package]]
 name = "ttf-parser"
 version = "0.25.1"