feat: Live Log Tail tab with level filtering and search

[vivekchand]

Closes #27

What

Adds a dedicated Logs tab to the ClawMetry dashboard with real-time log streaming, level-based filtering, full-text search, and auto-scroll control.

How

• Added page-logs HTML section in both dark and light themes with:
  • Level filter buttons (All / Error / Warn / Info / Debug) with color-coded chips
  • Full-text search input that filters log lines in real-time
  • Auto-scroll toggle checkbox
  • Line count selector (100 / 250 / 500 / 1000)
  • Stats bar showing total lines, error count, warning count, and stream status
• Updated renderLogs() to emit data-level and data-text attributes on each log line for client-side filtering
• Updated appendLogLine() to:
  • Apply current level/search filters to new streamed lines
  • Respect auto-scroll preference
  • Update stream status indicator
• Added setLogLevelFilter() and filterLogsView() functions for interactive filtering
• Enhanced .log-line CSS with hover state and border-radius in both themes
• Reuses existing /api/logs and /api/logs-stream SSE endpoints

Tests

53 tests pass (1 e2e test skipped, requires running instance)

+170 lines in dashboard.py