Add experimental custom resolver

[posva]

Summary by CodeRabbit

• New Features

  • Experimental per-route param parsers and a deterministic route resolver; new playground-experimental demo app with example pages, inspector and local JSON server; runtime definePage params support.

• Improvements

  • Routes export made readonly; richer date/number param parsing and stronger route/query typing; resolver generation and update flow improved for faster, more reliable updates.

• Tests

  • Expanded unit tests covering resolver ordering, param-parsers, and code generation.

• Chores

  • Dependency, workspace and config updates; new playground scripts, .gitignore and helper utilities.