feat: dashboard — activity tracker, pattern management, session timeline

[CalebisGross]

Three new dashboard panels for the web UI

1. Activity tracker live view

Show the current concept map from the watcher with live decay timers. Something like:

retrieval  ██████████░░  22min remaining
agent      ██████████░░  22min remaining  
mcp        ████░░░░░░░░  12min remaining
config     ░░░░░░░░░░░░  expired

Data source: GET /api/v1/activity (already exists). Add a decay countdown by computing window - (now - timestamp) client-side.

Makes it immediately obvious why context_boost is or isn't firing on recall.

2. Pattern management

Current state: patterns are displayed read-only in the dashboard. No way to archive, dismiss, or merge patterns.

Add:

• Archive/dismiss button per pattern (new API: DELETE /api/v1/patterns/{id} or POST /api/v1/patterns/{id}/archive)
• Visual indicator for pattern strength and age
• Project filter to show only patterns for the current project

3. Session timeline

Swimlane view of MCP sessions showing:

• Memories created (up arrows / green dots)
• Memories recalled (down arrows / blue dots)
• Feedback given (colored by quality: green=helpful, yellow=partial, red=irrelevant)
• Session duration and memory count

Data source: list_sessions + recall_session APIs already exist. Needs a new aggregated endpoint or client-side assembly.

4. Encoding pipeline monitor

Real-time chart showing:

• Queue depth over time
• Encoding latency histogram
• Dedup rate trend
• Coverage percentage

Data source: get_context metrics (already computed). Needs periodic polling or WebSocket push.

5. Salience distribution

Histogram of memory salience scores across the DB. Healthy system = nice spread. If everything clusters at 0.7 or 1.0, salience scoring isn't differentiating.

Data source: New query or extend GET /api/v1/stats with a salience histogram bucket.

Priority

Activity tracker and pattern management are highest value. Session timeline and encoding monitor are nice-to-haves. Salience histogram is a diagnostic tool for tuning.

[CalebisGross]

Phase 1 shipped in PR #314:

• Activity tracker live view: decay bars in the drawer with auto-refresh, color-coded by remaining time (green → yellow → pink)
• Pattern management: archive button on each pattern card with fade-out animation

Remaining (Phase 2): session timeline swimlane, encoding pipeline monitor, salience histogram — tracked as follow-ups.

[CalebisGross]

Phase 2 shipped in PR #316:

• Encoding Pipeline: funnel chart (raw → encoded → merged → active)
• Salience Distribution: stacked horizontal bars by tier with per-source color coding
• Session Timeline: swimlane chart showing session duration and memory count

All 5 panels from the original issue are now implemented across PRs #314 and #316.