Make type generation work offline with PGlite and test the CLI

[EEEEE213]

pgstrap generate and the initialized db:generate script now use in-memory PGlite by default, so types and SQL structure can be generated directly from migrations without a running PostgreSQL server. --no-pglite retains generation from the configured external database.

The integration tests also exposed a Bun/yargs initialization failure and Windows config-import failure; both are fixed. PGlite generation overrides all supported connection URI variables while dumping, restores them on failure, binds its gateway to loopback, and closes the temporary server and database.

Validation:

• Bun 1.4.2: all 8 tests pass (27 assertions), including default/explicit PGlite, external PostgreSQL opt-out, invalid migrations, and environment restoration after output failure. Offline cases point all four connection URI variables at an unreachable database.
• Built CommonJS CLI run with Node 24 on Windows: migration executed and both schema.d.ts and table.sql generated without PostgreSQL.
• Build passes with TypeScript 5.9.3 installed locally. The unconstrained upstream install selects TypeScript 7.0.2, which crashes tsup 7's declaration builder; dependency files are unchanged.
• Formatting of all changed TypeScript files and git diff --check pass. Repository-wide formatting still reports existing issues in untouched files.

AI-assisted implementation, locally tested. Fixes #2.

@algora-pbc /claim #2