[raiseCatError]

Stacked on #530. NMSh's own welcome now animates a still logo image (PNG, JPEG or WebP, transparency kept). The frames are generated in memory from the still, with no GIF and no files, and are played through the same path animated GIF/APNG welcome images already use.

• Presets: Assemble (sparks gather and the logo forms out of their light), Shine, Glow pulse, Glitch, Embers.
• Play: Once at startup (about 1.4–2.1 s) or Gentle loop. The loop stops after 30 s, on typing, or when the window loses focus.
• Defaults: Off by default. The output is byte-identical when Off, and Reduced Motion or Effects Off show the still image.
• Budgets: generation is seeded and fits the existing animation limits (75 frames, 32 MiB, 5 s).
• Settings: Welcome Studio › Animation has two rows, Logo animation and Play.

Also in this PR, following the maintainer's request for modern UI only:

• renderValueControl('bool') now uses the shared checkmark (✔ / ·) instead of a radio-style (*).
• AGENTS.md gains a permanent "Modern controls only" rule naming the shared pickers, toggles and reviews.
• tests/uiConsistency.test.ts fails on hand-drawn [x]/[ ] or (*)/( ) marks. A red check confirmed it catches the old toggle.

Physical QA was done in a disposable Kitty 0.49.2 with forced Kitty graphics, using a generated test logo. Screenshots are in the evidence folder welcome-anim/.

Known gaps:

• On Auto, a late Kitty graphics probe reply can drop the welcome to character art. That reply can also land in the composer (existing behavior in src/host/probe.ts).
• Any keypress turns the welcome image into character art (existing cancelMotion).
• Sixel and Ghostty were not tested physically.

Tests: 89 related focused tests pass, plus the new welcomeLogoAnimation tests; tsc is clean.