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

computed.go

@@ -1,7 +1,6 @@
 package via
 
 import (
-	"fmt"
 	"strconv"
 	"strings"
 
@@ -51,5 +50,5 @@ func (s *computedSignal) recompute() {
 }
 
 func (s *computedSignal) patchValue() string {
-	return fmt.Sprintf("%v", s.lastVal)
+	return s.lastVal
 }