docs(bf-5txw9): verify path normalization already implemented in fixture_discovery

The normalize_path() function in fixture_discovery.rs (lines 56-114) already provides:
- Symlink resolution via canonicalize()
- Relative component handling (., ..)
- Absolute path conversion
- Fallback for non-existent paths

All 13 tests pass, including specific normalization verification tests:
- test_fixture_paths_are_absolute
- test_normalized_paths_no_relative_components
- test_normalized_paths_work_in_test_context
- test_normalized_paths_are_consistent
- test_category_discovery_returns_normalized_paths

Acceptance criteria met:
✅ Paths are absolute or consistently test-relative
✅ Symlinks and relative components resolved
✅ Paths work in test context

No code changes required - verification note documents existing implementation.

notes/bf-5txw9.md

@@ -0,0 +1,53 @@
+# bf-5txw9: Add path normalization for fixture discovery
+
+## Summary
+Path normalization was already implemented in the fixture_discovery.rs module as part of the basic discovery implementation (bf-6cc3z).
+
+## Implementation Status
+The `normalize_path()` function (lines 56-114 in fixture_discovery.rs) provides comprehensive normalization:
+
+### Features Implemented
+1. **Symlink Resolution**: Uses `Path::canonicalize()` to resolve symlinks and get absolute paths
+2. **Relative Component Handling**: Component-based normalization removes `.` and `..` components
+3. **Absolute Path Conversion**: Converts relative paths to absolute paths based on current directory
+4. **Fallback for Non-existent Paths**: Handles paths that don't exist gracefully with component-based normalization
+
+### Code Coverage
+The normalization is applied in:
+- `discover_fixtures_flat()` - line 195
+- `discover_fixtures_in_dir()` - line 233
+- All discovery functions transitively through these
+
+## Verification - Test Results
+All 13 fixture discovery tests pass:
+
+```
+running 13 tests
+test tests::test_category_discovery_returns_normalized_paths ... ok
+test tests::test_discover_fixtures_by_category ... ok
+test tests::test_discover_fixtures_flat ... ok
+test tests::test_discover_all_fixtures ... ok
+test tests::test_fixture_categories ... ok
+test tests::test_fixture_sorting ... ok
+test tests::test_fixture_paths_are_absolute ... ok
+test tests::test_fixtures_root_exists ... ok
+test tests::test_nonexistent_category ... ok
+test tests::test_fixture_statistics ... ok
+test tests::test_normalized_paths_are_consistent ... ok
+test tests::test_normalized_paths_no_relative_components ... ok
+test tests::test_normalized_paths_work_in_test_context ... ok
+
+test result: ok. 13 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
+```
+
+## Acceptance Criteria Status
+- ✅ **Discovered paths are absolute or consistently test-relative**: `test_fixture_paths_are_absolute` verifies all paths are absolute
+- ✅ **Symlinks and relative components are resolved**: `test_normalized_paths_no_relative_components` verifies no `/./` or `/../` in paths
+- ✅ **Paths work in test context**: `test_normalized_paths_work_in_test_context` verifies all normalized paths exist and are readable
+
+## Files
+- `crates/pdftract-cli/tests/fixture_discovery.rs` - Lines 56-114 (normalize_path function), applied at lines 195, 233
+- Tests: Lines 438-514 cover normalization verification
+
+## Conclusion
+The path normalization requirement for bf-5txw9 is already fully implemented and tested. No additional code changes are required.