feat: FRED bootstrap + Calendar page complete rebuild

- backend/services/fred_bootstrap.py: fetch 11 FRED series (PAYEMS, UNRATE, CPI, PCE, FEDFUNDS, ICSA, GDP, HY spread, T10Y2Y, T10Y3M) from public CSV endpoint — no API key needed; computes rolling z-scores and upserts into economic_events table
- backend/routers/eco.py: new /api/eco router with bootstrap (POST + status GET), events list with full filtering (date range, category, series, min z-score, direction, sort/pagination), series catalog, and db status endpoints
- backend/main.py: register eco router
- frontend/src/pages/CalendarPage.tsx: complete rewrite — real data table from /api/eco/events, Bootstrap FRED button with live polling, filter bar (date range, category, series chips, |z| threshold, direction), sort by date/z-score/series, pagination, z-score badges with color coding, sidebar with series inventory + geo alerts + z-score guide

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/main.py

@@ -13,6 +13,7 @@ from routers import logs as logs_router
 from routers import var as var_router
 from routers import reports as reports_router
 from routers import institutional as institutional_router
+from routers import eco as eco_router
 from services.database import init_db, get_config, cleanup_stale_running_cycles
 import os
 import logging
@@ -134,6 +135,7 @@ app.include_router(impact_router.router)
 app.include_router(cycle_actions_router.router)
 app.include_router(market_events_router.router)
 app.include_router(ai_desks_router.router)
+app.include_router(eco_router.router)
 
 
 @app.get("/")