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/2026-01-05-000100_add_location_history/down.sql

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+DROP TABLE IF EXISTS location_history;

migrations/2026-01-05-000100_add_location_history/up.sql

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+CREATE TABLE location_history (
+    id INTEGER PRIMARY KEY NOT NULL,
+    timestamp BIGINT NOT NULL,
+    latitude REAL NOT NULL,
+    longitude REAL NOT NULL,
+    accuracy INTEGER,
+    activity TEXT,
+    activity_confidence INTEGER,
+    place_name TEXT,
+    place_category TEXT,
+    embedding BLOB,
+    created_at BIGINT NOT NULL,
+    source_file TEXT,
+    UNIQUE(timestamp, latitude, longitude)
+);
+
+CREATE INDEX idx_location_timestamp ON location_history(timestamp);
+CREATE INDEX idx_location_coords ON location_history(latitude, longitude);
+CREATE INDEX idx_location_activity ON location_history(activity);