fix: resolve unimplemented!() paths in wait_for.rs and uri.rs

[adolago]

Summary

Two core modules contain unimplemented!() macros. These are NOT in the main execute() paths so they don't cause runtime panics during normal use, but they should be resolved before GA.

Locations

• src/modules/wait_for.rs — unimplemented!() in a non-critical code path
• src/modules/uri.rs — 2 instances of todo!/unimplemented! in non-critical paths

Acceptance criteria

• All unimplemented!() and todo!() macros replaced with proper implementations or explicit ModuleError::Unsupported returns
• No panicking paths remain in any module
• Existing tests continue to pass

Priority

Low — not in execute() hot paths