feat: implement desktop chat composer and capability states

[Mathis (echobt)]

What changed

Implement D03 local desktop Chat: no-provider action gating and provider navigation, keyboard model picker below the heading, eight-line composer using native CSS field sizing, elapsed busy strip and actual cancellation, sidebar/Cmd+N new-chat flow without duplicate content-header actions, direct capability empty states, and duplicate prompt-error suppression. Preserve the existing Code composer contract.

Targets ux/desktop-01-kit (#70), not main.

How to try it

bun run build && bun run start; open #/home in local mode. Fill 2,500 characters, add a provider, use model-chip arrow keys/Enter/Escape, send through a slow provider and press Stop. Direct links to canvas/search-results/deep-research/image-gen/share/temp-chat show the shared local capability state.

Honest states

No-model sends/voice are disabled with aria-disabled. Add a provider navigates to provider setup. Direct local unsupported capabilities name the feature and offer provider setup. Existing session errors remain product-language cards.

Verification

Typecheck, ESLint, i18n audit and production build pass. Unit suite: 520 passed, one pre-existing conditional skip. Seven new registry/capability tests pass.

Real Electron Playwright: 1440/960 widths, light/dark themes, fresh profiles. Verified no-model controls/navigation, 2,500-character draft height 222 px with 20 px line-height, send bottom within 1 px, no textarea scrollbar arrows, nonintersecting picker with changed keyboard selection and Escape focus, timer 00:00 to 00:01, Stop in 43-100 ms, unchanged composer height 82 px, sidebar New chat/Cmd+N, six direct capability routes. Evidence: /root/omo-herdr-wt/hermes-docs-qa-docs-attempt2/.omo/evidence/D03/final-results.json and PNGs.

Full E2E: 88 passed, 156 failed. Not green. Shared /tmp inode exhaustion plus legacy Chat route integration caused failures; focused recovery runs also blocked. No failing assertion was removed or weakened.

Risk and rollback

Draft until parent applies the supplied shell patch outside D03's file allowlist: unavailable navigation remains visible and legacy #/chat needs shell dispatch after registry removal. Exact patch: /root/omo-herdr-wt/hermes-docs-qa-docs-attempt2/.omo/evidence/D03/parent-shell.apply_patch. Parent also owns required AGENTS.md update. Full DSK-07 not accepted until integration and rerun.

Remote composer/native account capability parity remains an M11 integration dependency with M12 backend endpoints; M09/M10 not claimed integrated. No merge/deploy.

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Attestation

• Rules read. I read AGENTS.md and relevant .rules/ files. Scoped changes follow them; parent-owned documentation/integration remains pending.
• Error copy is product language. No new vendor/error internals in user copy.
• Responsive and themed. Verified 960x900 and 1440x900 light/dark; minimum 960x640 not yet verified.
• Security holds. No keys/session material added to source; renderer boundaries preserved; local mode requires no account.
• Docs updated in this PR. AGENTS.md outside allowed scope; parent-owned update pending.
• I verified this carefully. Real Electron acceptance and local checks run; full regression currently red, remaining integration recorded above.

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⚙️ Run configuration

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📥 Commits

Reviewing files that changed from the base of the PR and between 00e965a and a505464.

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📒 Files selected for processing (12)

• packages/app/src/screens/chat/desktop-chat.test.ts
• packages/app/src/screens/chat/index.tsx
• packages/app/src/screens/chat/live-chat.tsx
• packages/app/src/screens/chat/model-composer.tsx
• packages/i18n/locales/de/composer.json
• packages/i18n/locales/en/composer.json
• packages/i18n/locales/es/composer.json
• packages/i18n/locales/fr/composer.json
• packages/i18n/locales/ja/composer.json
• packages/i18n/locales/ko/composer.json
• packages/i18n/locales/pt-BR/composer.json
• packages/i18n/locales/zh-Hans/composer.json

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[blacksmith-sh]

Found 16 test failures on Blacksmith runners:

Failures

Test	View Logs
tests/e2e/ bot-safety.spec.ts:102:3 › Preview Bot shares saved look, draft, pause and activity — 1 440 dark	View Logs
tests/e2e/ bot-safety.spec.ts:102:3 › Preview Bot shares saved look, draft, pause and activity — 1 440 light	View Logs
tests/e2e/ bot-safety.spec.ts:102:3 › Preview Bot shares saved look, draft, pause and activity — 9 60 dark	View Logs
tests/e2e/ bot-safety.spec.ts:102:3 › Preview Bot shares saved look, draft, pause and activity — 9 60 light	View Logs
tests/e2e/ chat-missing.spec.ts:18:1 › a failed deferred delete restores the Chat with an error	View Logs
tests/e2e/ chat-missing.spec.ts:43:40 › Deleted Chat shows truthful missing-page recovery — dark	View Logs
tests/e2e/ chat-missing.spec.ts:43:40 › Deleted Chat shows truthful missing-page recovery — light	View Logs
tests/e2e/ components.spec.ts:4:40 › Components catalog: families, variants and three-preview ceil ing (dark)	View Logs
tests/e2e/ components.spec.ts:4:40 › Components catalog: families, variants and three-preview ceil ing (light)	View Logs
tests/e2e/ composer-safety.spec.ts:25:3 › Code keeps cancelled and no-model drafts, locks pending submits — dark	View Logs

...and 6 more test failures. View all on Blacksmith

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