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

ci-check.sh

@@ -6,9 +6,13 @@ set -o pipefail
 ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 cd "$ROOT"
 
-echo "== CI: Format code =="
-go fmt ./...
-echo "OK: formatting complete"
+echo "== CI: Check formatting =="
+if [ -n "$(gofmt -l .)" ]; then
+  echo "ERROR: files not formatted:"
+  gofmt -l .
+  exit 1
+fi
+echo "OK: all files formatted"
 
 echo "== CI: Run go vet =="
 if ! go vet ./...; then