feat(branding): identify yngatech distribution builds

[incognitojam]

What Changed

• Keeps the T3 Code product name while adding an always-visible yngatech distribution badge in the sidebar.
• Preserves Latest/Nightly/Dev as a separate build-stage axis. The badge absorbs Nightly or Dev only when stage artwork is disabled.
• Applies a restrained petrol/teal fork signature to Nightly and Dev artwork and to the production, Nightly, and development app icons across macOS, iOS, web, and Windows.
• Shows yngatech/t3code, app version, and build commit in the in-app About/update UI; the native desktop About panel keeps its standard name, version, and commit metadata.
• Threads the resolved artifact commit into the web bundle during desktop packaging.

Why

Fork builds previously looked indistinguishable from upstream, making it easy to confuse which distribution or update provenance was running. This adds a persistent distribution cue while retaining the familiar T3 Code identity and existing build-stage system.

UI Changes

Build	Before	After
Latest
Nightly
Dev

The sidebar keeps the existing T3 wordmark and stage geometry, adding the compact distribution badge and matching teal stage palettes. No chat, settings content, motion, or interaction behavior changed.

Verification

• vp test run apps/web/src/branding.test.ts apps/desktop/src/app/DesktopAppIdentity.test.ts scripts/build-desktop-artifact.test.ts — 57 tests passed
• Web, desktop, and scripts typechecks passed
• vp run icons:check — all 25 generated assets current
• macOS exports verified at 1024×1024 with an 824×824 opaque body inset 100px on every side
• git diff --check

Checklist

• This PR is small and focused
• I explained what changed and why
• I included before/after screenshots for UI changes
• No animation or interaction changes; video is not applicable

Implemented with GPT-5.6 in the Codex harness through T3 Code.

[incognitojam]

Superseded by #29, which contains only the functional identification, label semantics/tests, About provenance, and commit-hash injection changes. The icon, favicon, palette, and sidebar-backdrop asset work will follow in a separate PR.