release: 2026.2.3

[aivangogh]

Summary

• add Philippine postal/ZIP-code data and lookup APIs
• document the PSGC Revision 1 10-digit structure and Q2 2026 national summary
• document all public function signatures and exported TypeScript shapes
• link the PSA PSGC and postal-code data sources
• bump package metadata to 2026.2.3 with postal/ZIP discovery keywords

Verification

• pnpm typecheck
• pnpm build
• pnpm exec vitest run --exclude ".worktrees/**" (75 tests passed)