* Set default query timeout to 2 minutes and enforce minimum.
* Add statement_timeout for PostgreSQL DSN.
* Implement busy timeout for SQLite with a minimum of 2 minutes.
* Enforce minimum connection timeouts of 10 minutes for server instance.
- Add ServersConfig and ServerInstanceConfig structs
- Support configuring multiple named server instances
- Add global timeout defaults with per-instance overrides
- Add TLS configuration options (SSL cert/key, self-signed, AutoTLS)
- Add validation for server configurations
- Add helper methods for applying defaults and getting default server
- Add conversion helper to avoid import cycles
