fix: use PGlite by default for db generation

[iliasaberkane6-lab]

Summary

• make the existing PGlite generation path the default, so db:generate does not require a running PostgreSQL server
• keep external PostgreSQL generation available via --no-pglite
• turn the PGlite generation test into a regression test that omits the flag
• document the new default and escape hatch

Verification

• bun test (3 pass, 0 fail)
• bun run format:check
• bun run build
• git diff --check

@algora-pbc /claim #2

Closes #2

[iliasaberkane6-lab]

@algora-pbc /claim #2

[iliasaberkane6-lab]

Quick status note: all local verification passed (bun test, bun run format:check, bun run build, git diff --check). The three GitHub Actions runs currently show action_required with no jobs created, which appears to require maintainer approval before CI can execute for this first-time contribution. When convenient, could you approve the workflow runs and review the PR? Thanks!