fix: nil-close bug, stale docs, dead code, and tracked binaries

- Fix potential nil file.Close() panic in devModePersist/devModeRemovePersisted
  by extracting loadDevModeMap/saveDevModeMap helpers with proper defer
- Remove tracked binaries (pathparams 10.8 MB, shake.db 22 MB) and consolidate
  .gitignore with a wildcard pattern covering all 19 examples
- Remove stale reaper reference in README (removed in dc56261), update example
  count from 14 to 19, fix OnChange debounce claim in docs
- Fix typos: "percist"→"persist", "percisted"→"persisted", "tmplates"→"templates"
- Remove dead code: commented import in signal_test.go, unnecessary fmt.Sprintf
  in computed.go, commented picocss imports and no-op Config calls in examples
- Replace go fmt with gofmt -l check in ci-check.sh to fail on unformatted code
  instead of silently reformatting

internal/examples/shakespeare/main.go

@@ -22,6 +22,9 @@ type ShakeDB struct {
 	findByTextStmt *sql.Stmt
 }
 
+// Prepare opens shake.db, a ~22 MB SQLite database of Shakespeare's works.
+// Download from https://github.com/nicholasgasior/gopher-fizzbuzz/raw/master/shake.db
+// and place it in this directory before running.
 func (shakeDB *ShakeDB) Prepare() {
 	db, err := sql.Open("sqlite3", "shake.db")
 	if err != nil {