Add Insights Dashboard with usage analytics

New sidebar section showing rich analytics from the sessions database:
- Overview grid: sessions, messages, tokens (input/output/cache), active
  time, avg session duration, avg messages per session
- Model breakdown: sessions and total tokens per model
- Platform breakdown: CLI vs Telegram etc with session/message counts
- Top tools bar chart: ranked by call count with percentages
- Activity patterns: day-of-week bars and hourly heatmap
- Notable sessions: longest, most messages, most tokens, most tool calls
  with clickable links to open in Sessions browser
- Time period selector: 7/30/90 days or all time

Also adds ROADMAP.md documenting the full feature expansion plan.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scarf/docs/ROADMAP.md

@@ -0,0 +1,58 @@
+# Scarf — Feature Roadmap
+
+## Tier 1 — High Value, Data Already Available
+
+### 1. Insights Dashboard
+Rich usage analytics pulled from the sessions and messages SQLite tables:
+- Overview stats: sessions, messages, tool calls, tokens, active time, avg session duration
+- Model breakdown: sessions and tokens per model
+- Platform breakdown: CLI vs Telegram vs Discord usage
+- Top tools chart: ranked tool usage with call counts and percentages
+- Activity patterns: sessions by day-of-week, peak hours heatmap
+- Notable sessions: longest, most messages, most tokens, most tool calls
+- Time period selector: last 7/30/90 days
+
+### 2. Tool Management Panel
+- List all toolsets with enabled/disabled status and descriptions
+- Toggle switches to enable/disable tools (via `hermes tools enable/disable`)
+- Per-platform tool configuration
+- MCP tool status
+
+### 3. Session Management Enhancements
+- Rename sessions from the Sessions browser (via `hermes sessions rename`)
+- Delete sessions (via `hermes sessions delete`)
+- Export sessions to JSONL (via `hermes sessions export`)
+- Session stats card (total count, DB size, per-platform breakdown)
+
+## Tier 2 — Medium Value, New Service Code Required
+
+### 4. Skills Hub
+- Search remote registries for new skills (6 sources)
+- Install/uninstall skills from GUI
+- Skill update indicator
+- Trust level badges (builtin, local, hub)
+
+### 5. Gateway Control Center
+- Start/stop/restart gateway from GUI
+- Real-time status: PID, uptime, connected platforms
+- Pairing management: view approved users, approve/revoke
+- Platform status per messaging service
+
+### 6. System Health View
+- Mirror `hermes status` and `hermes doctor` output
+- API key validation, auth provider status, external tools
+- Update available indicator
+
+## Tier 3 — Nice to Have
+
+### 7. Profile Management
+- List/create/switch profiles (isolated Hermes instances)
+
+### 8. Plugin Management
+- Install from Git, enable/disable, update
+
+### 9. MCP Server Management
+- Add/remove/test MCP servers, toggle tools per server
+
+### 10. Config Editor
+- Structured form editor for config.yaml with validation