feat(planner): wire DuckDB analytics + market-data endpoint

- analytics.py: open/close_analytics_db registered in app lifecycle
- GET /planner/api/market-data?city_slug=<slug>: returns per-city
  planner defaults from DuckDB planner_defaults serving table

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

CHANGELOG.md

@@ -6,6 +6,13 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 ## [Unreleased]
 
+### Added
+- `analytics.py`: DuckDB read-only reader (`open_analytics_db`, `close_analytics_db`,
+  `fetch_analytics`) registered in app lifecycle (startup/shutdown)
+- `GET /planner/api/market-data?city_slug=<slug>`: returns per-city planner defaults from
+  DuckDB `planner_defaults` serving table; falls back to `{}` when analytics DB unavailable
+
+
 ### Added
 - `transform/sqlmesh_padelnomics` workspace member: SQLMesh 4-layer model pipeline over DuckDB
   - Raw: `raw_overpass_courts`, `raw_playtomic_tenants`, `raw_eurostat_population`