feat(cli): add express checkup command with direct PostgreSQL health checks + fix H004 and A003

Summary

Adds express checkup command to the CLI that generates PostgreSQL health check reports directly from the database, without requiring Prometheus infrastructure.

Key features:

• New postgresai checkup command for direct database health analysis
• Support for 11 check types: A002, A003, A004, A007, A013, D004, F001, G001, H001, H002, H004
• Automatic upload to PostgresAI Console (optional, requires API key)
• JSON output mode for scripting and automation
• Build-time embedding of SQL metrics for smaller bundle size

Changes

CLI (cli/)

• Added checkup command with connection handling, SSL fallback, and progress spinner
• Added set-default-project command for storing upload preferences
• New modules: checkup.ts (report generators), checkup-api.ts (RPC client), metrics-loader.ts
• Build script to embed metrics.yml at compile time
• Preserves defaultProject on re-authentication

Reporter (reporter/)

• Added generation_mode field to distinguish "express" vs "full" reports
• Added redundant_to array to H004 schema for better index relationship tracking
• New helper methods for filtering A003 settings by report type (D004, F001, G001)

Metrics (config/pgwatch-prometheus/metrics.yml)

• Enhanced settings metric with setting_normalized and unit_normalized fields
• Updated redundant_indexes to output redundant_to_json with index sizes
• Added index_definition to unused_indexes metric

https://gitlab.com/postgres-ai/platform/-/issues/346