Fix shared exception constructors

[pradhankukiran]

Fixes #196

• Adds a new GlobalExceptionGenerator that emits a single _server/exceptions.ts with shared runtime exception classes, so all controllers reference the same constructor

• Updates LocalActionGenerator to import and re-export from the global module instead of defining its own exception classes per controller

• Fix make test-scripts failing with ModuleNotFoundError: No module named 'scripts'

• Fix root uv run pytest collecting tests from subprojects and Jinja2 templates

• Silence pytest-asyncio deprecation warnings across all subprojects