Fix streaming drafts, UTC timestamps and permission review

[rcarmo]

Fix streaming drafts, UTC timestamps and permission review

PR: #20
Base: main
Head: review/ui-streaming-permissions

First PR of the published stack: #20 UI → #21 Windows → #22 FFI. Neither child is required to review this UI diff. CI/review follow-up is handed to the maintainer; no automatic merge is enabled.

Changes

• Accumulate explicit append-mode draft events; preserve replacement snapshots and avoid double consumption of expanded deltas.
• Interpret SQLite CURRENT_TIMESTAMP strings as UTC. Keep explicit timezone offsets, periodically update ages and show absolute local time on hover.
• Remove agent capability diagnostics from the composer.
• Render native-shaped permission requests as actions and arguments while retaining ACP/Pi payload compatibility. Keep exact CLI text visible and wrapped, add a LAN-HTTP-compatible Copy action, visible warnings, fixed decision footer and keyboard focus handling.
• Support optional free-form response text and exact request-close SSE events without changing existing response option IDs or granting permissions.
• Preserve canonical UX fixture LF bytes on Windows. Exempt generated JS from whitespace rewriting.
• Fix four pre-existing Python E701/E702 style violations in message retrieval so the existing whole-repository lint gate can run. No behavior change in those four edits.
• Deduplicate successful queue steering per chat/turn/row, including after HTTP acknowledgement; failed submissions remain retryable.
• Ship docs/BROWSER_REVIEW.md and link it from the README.

No Copilot SDK dependency, native adapter, token handling, upload-ownership change or LAN deployment wrapper is included. Copilot-shaped display normalization is passive; it can render any matching request payload without starting an adapter.

Verification

• 56 frontend tests pass; frontend ESLint/build pass.
• Whole-repository Ruff passes; 7 message-tool tests pass.
• Added browser fixtures for word-chunk accumulation, replacement snapshots, expand/collapse deduplication, UTC age updates in Lisbon/UTC/New York, and permission layout/copy/focus at desktop, phone and landscape sizes.
• Hosted Linux Python and installed-package checks passed. Initial Chromium/WebKit run: 511 passed, 2 skipped, 5 failed (four assertions still expected the deliberately removed capability strip; one WebKit steering duplicate). Corrected those contracts and the deduplication implementation; full browser CI is rerunning at f382691.
• Integrated Edge fixture checks passed for the above flows. Latest CI: https://github.com/rcarmo/vibes/actions/runs/37045198117
• The UI-only branch retains upstream's Windows fcntl startup limitation. An attempted system-metrics app smoke failed at that unchanged POSIX import; it is addressed by the separate Windows PR. This PR is not labelled full-Windows-suite green.

Review focus

draft-stream.js, timestamps.js, agent-request-details.js, permission-clipboard.js, status.js and the scoped style overrides in styles.css contain the maintained code. Generated JS/CSS/maps and the HTML asset hash were rebuilt for this branch. Approval callbacks and IDs are unchanged; tests never approve real user requests.