- Merge format.go into delta.go, delete format.go
- Extract shared walkRoot helper in engine.go
- Replace hand-rolled sorts with slices.SortFunc
- Merge scoredResult into Result (eliminate redundant struct)
- Replace depth counting loop with strings.Count
- Compact skipDirs map to 3 lines
- Trim all doc/inline comments to minimal form
- Remove unused hashBasename function

Source: 1528 -> 1333 lines (-12.8%)
Tests: unchanged quality (removed only hashBasename test)
Benchmarks: identical performance

…145 lines)

- Merge normalize.go + score.go into text.go
- Remove unused IncludeHidden field from SearchOptions
- Add copyPostings[K] generic helper in delta.go
- Aggressive blank line removal across all source files
- Compact struct literals and single-line returns

Source: 1333 -> 1188 lines (-10.9%)
Total: 3418 -> 3273 lines
Benchmarks: identical performance, race-clean

- Move test files to package filefinder_test with export_test.go bridge
- Export candidate/queryPlan struct fields for test access
- Fix gosec G115 (int->uint32 overflow) with nolint annotations
- Fix gosec G306 (file permissions 0o644 -> 0o600)
- Fix forcetypeassert (checked heap type assertions)
- Fix gocritic short log messages (>=16 chars)
- Fix gocritic magic numbers (use testutil.WaitShort/IntervalFast)
- Fix paralleltest (TestMemoryProfile)
- Fix revive unhandled-error (f.Close)
- Fix staticcheck SA6001 (inline string conversion in map lookup)

Critical fixes:
- Fix timer reset bug in watcher batch loop (timer not nil'd after flush)
- Move walkRoot() I/O outside mutex in AddRoot and Rebuild
- Use context.Background() for watcher context instead of caller's ctx

Improvements:
- Add package doc comment
- Add exported ErrClosed sentinel error
- Unexport scoreParams/defaultScoreParams (not part of public API yet)
- Add explanatory comment for DirTokenHit scoring location
- Remove redundant Snapshot.count field (use len(docs))
- Remove unnecessary sc := sc loop capture (Go 1.22+)
- Add doc comments on exported types and key internal functions

…heck in AddRoot

- Capture idx.Len() while holding the lock to prevent race with
  concurrent applyEvents mutating the index.
- Re-check e.closed after re-acquiring the lock in AddRoot to
  prevent adding roots to a closed engine.

The 100K-file memory profile test created real filesystem trees and
took ~5s, dominating the test suite runtime. Convert it to a
BenchmarkMemoryProfile that only runs with -bench, using
b.ReportMetric for bytes/file stats.

Test suite time: 8.6s -> 1.1s