feat: [FE] Add stats cards and status bar to homepage

[Mbeaulne]

Description

Add a row of stats cards at the top of the homepage showing aggregate run and pipeline counts. Below the cards, display a horizontal status bar visualizing the run status breakdown.

Depends on: TangleML/tangle#177

Stats cards

Card	Value	Click action
Total Runs	total_runs	Show all runs (no filter)
Active	RUNNING + PENDING + QUEUED	Filter to active runs
Succeeded	SUCCEEDED count	Filter to succeeded runs
Failed	FAILED + SYSTEM_ERROR count	Filter to failed runs
Cancelled	CANCELLED count	Filter to cancelled runs
Pipelines	total_pipelines	Switch to Pipelines tab

Behavior

• Stats reflect the currently active filters — if the user filters by date range or "created by me", the stats cards update to match
• Clicking a card adds/toggles that status filter on top of any existing filters (date range, user, etc.)
• Active/selected card is visually highlighted
• Cards show loading skeletons while stats are fetching
• Stats auto-refresh every 60s (matching backend cache TTL)
• Use existing status color scheme (green=succeeded, red=failed, blue=running, etc.)
• Horizontal status bar below cards shows proportional breakdown

Integration with filters

The stats endpoint (GET /api/pipeline_runs/stats) accepts the same filter_query as the list endpoint. When the user applies filters (date range, created_by, pipeline name, annotations), the frontend should pass those same filters to the stats endpoint so the cards reflect the filtered dataset.

Reusable existing code

• src/utils/executionStatus.ts — status grouping logic, color mappings, priority ordering
• src/components/shared/Status/TaskStatusBar.tsx — segmented bar visualization pattern

Relevant files to modify

• src/routes/Home/Home.tsx — add stats section above tabs
• src/components/Home/RunSection/RunSection.tsx — accept filter from parent via search params