Add Google Takeout data import infrastructure

Implements Phase 1 & 2 of Google Takeout RAG integration:
- Database migrations for calendar_events, location_history, search_history
- DAO implementations with hybrid time + semantic search
- Parsers for .ics, JSON, and HTML Google Takeout formats
- Import utilities with batch insert optimization

Features:
- CalendarEventDao: Hybrid time-range + semantic search for events
- LocationHistoryDao: GPS proximity with Haversine distance calculation
- SearchHistoryDao: Semantic-first search (queries are embedding-rich)
- Batch inserts for performance (1M+ records in minutes vs hours)
- OpenTelemetry tracing for all database operations

Import utilities:
- import_calendar: Parse .ics with optional embedding generation
- import_location_history: High-volume GPS data with batch inserts
- import_search_history: Always generates embeddings for semantic search

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

migrations/2026-01-05-000000_add_calendar_events/up.sql

@@ -0,0 +1,20 @@
+CREATE TABLE calendar_events (
+    id INTEGER PRIMARY KEY NOT NULL,
+    event_uid TEXT,
+    summary TEXT NOT NULL,
+    description TEXT,
+    location TEXT,
+    start_time BIGINT NOT NULL,
+    end_time BIGINT NOT NULL,
+    all_day BOOLEAN NOT NULL DEFAULT 0,
+    organizer TEXT,
+    attendees TEXT,
+    embedding BLOB,
+    created_at BIGINT NOT NULL,
+    source_file TEXT,
+    UNIQUE(event_uid, start_time)
+);
+
+CREATE INDEX idx_calendar_start_time ON calendar_events(start_time);
+CREATE INDEX idx_calendar_end_time ON calendar_events(end_time);
+CREATE INDEX idx_calendar_time_range ON calendar_events(start_time, end_time);