feat(activity-log): phase 6 - dashboard widget + settings panel + docs

- Dashboard 'Recent Activity' widget: latest 5 entries, live prepend, 'View all' -> Activity tab
- Settings 'Activity Log' panel: retention (enabled/max_days/max_entries) GET/PUT, clear (confirm + auth-required toast), CSV/JSON export
- audit-log vs ephemeral debug Log Viewer distinction note + cross-links
- public helpers fetchRecentEntries/renderCompactEntry on activity-log.ts (reused, no dup markup)
- README Activity Log section; i18n across en/ru/zh
- review fixes: clear 401 surfaces toast; empty widget transitions on first live event

plans/activity-log/CONTEXT.md

@@ -70,3 +70,4 @@ Phase 2 landed (2026-06-09): `core/activity_log/` package (`context.py`, `record
 Phase 4 landed (2026-06-09): schemas (`api/schemas/activity_log.py`), routes (`api/routes/activity_log.py`: list/export/settings/clear), router registration in `api/__init__.py`, `get_seq_for_id` helper on `ActivityLogRepository`. 49 new tests — all green. Full suite 2486 passed, 2 skipped, 0 failed. Ruff clean. Pagination bug found and fixed (limit+1 probe must drop oldest row when has_more, not tail).
 Phase 3 landed (2026-06-09): instrumented all four categories — entity CRUD via `fire_entity_event` choke-point (`dependencies.py`), auth failures + WS session in `auth.py`, device online/offline in `device_health.py`, device discovered/lost in `discovery_watcher.py`, ADB connect/disconnect in `system_settings.py`, capture start/stop (individual + bulk) in `output_targets_control.py`, scene/playlist/automation activate in their respective route/engine files, backup/restore/delete + restart/shutdown/update/calibration/settings in `backup.py`/`update.py`/`calibration.py`; all 11 entity delete handlers pass `entity_name` to `fire_entity_event`; 22 new tests (security: token never in any field, explicitly asserted) — all green. Full suite 2369 passed, 2 skipped, 0 failed. Ruff clean. Complete (category, action) inventory in phase-3-instrumentation.md Handoff section.
 Phase 5 landed (2026-06-09): Activity tab frontend — `features/activity-log.ts` (loadActivityLog, filter toolbar with category/severity chips + presets + debounced search + date range + actor/entity-type text fields, keyset-paginated list, expandable detail drawer, live-prepend via `server:activity_logged`, authed CSV/JSON blob export); `core/ui.ts` additions (`formatTimestamp`, `formatRelativeTime`); `core/icon-paths.ts` + `core/icons.ts` additions (scrollText/audit, circleAlert, info, filter, xCircle); `core/tab-registry.ts` registered; `templates/index.html` tab button + panel; `app.ts` + `global.d.ts` wired; `static/css/activity-log.css` (precision-ledger design, category color rail, live-dot pulse, detail drawer, responsive breakpoints); all three locales updated (activity_log.* + time.* relative-time keys + tour.activity_log); `features/tutorials.ts` getting-started tour extended. `tsc --noEmit` clean, `npm run build` passes. Reusable helpers for Phase 6 documented in phase-5-frontend-tab.md Handoff section.
+Phase 6 landed (2026-06-09): Dashboard "Recent Activity" widget (live SSE, View-all link, `.dal-*` CSS, loading/empty states) + Settings "Activity Log" panel (enabled toggle, max_days/max_entries, Save toast, authed CSV/JSON export, confirmed Clear, audit-vs-debug cross-links) + 32 i18n keys per locale + README "Activity Log" section. `tsc --noEmit` clean, `npm run build` passes. All six phases complete — feature ready for final review.