Closes #11
Summary
- replace the inert watch stub with portable source and test snapshots
- rerun changed or newly added tests directly and map source edits through transitive relative imports
- fall back to the full suite for deletions, renames, unresolved module imports, and unmapped source changes
- retain debounce behavior, print every selection reason, and add the interactive r full-rerun command
- document the affected-test strategy and safe fallback rules
Verification
- zig fmt --check .
- zig build test
- zig build examples
- zig build -Dtarget=x86_64-windows