fix: repair Renovate config, convert Makefile to go run, update GitHub Actions (#120)

* fix: repair Renovate config and convert Makefile to go run (#117)

- Remove non-existent `github>renovatebot/presets:golang` preset that
  broke Renovate PR creation
- Replace deprecated `fileMatch` with `managerFilePatterns` in
  customManagers
- Rewrite regex to match new Makefile pattern (renovate comment above
  version variable assignment)
- Fix `matchFileNames` glob pattern (`*.mk` -> `**/*.mk`)
- Convert all tool invocations from `go install` + global binary to
  `go run tool@version` for reproducible builds
- Convert npm global tools to `npx --yes` invocations
- Remove `dev-deps` and `check-deps` targets (tools auto-download)
- Add mdformat pre-commit hook with GFM support and config
- Add `fmt-md` Makefile target for manual markdown formatting
- Update local golangci-lint pre-commit hook to use `go run`
- Apply golangci-lint v2.10.1 auto-fixes (fmt.Fprintf optimization)
- Add nolint:gosec annotations for legitimate exec.Command usage
- Exclude .serena/ from mdformat and megalinter
- Add markdown indent_size=unset in .editorconfig for CommonMark compat

* chore(deps): update GitHub Actions to latest versions

- anthropics/claude-code-action: v1.0.34 -> v1.0.64
- actions/setup-go: v6.2.0 -> v6.3.0
- actions/upload-artifact: v6.0.0 -> v7.0.0
- goreleaser/goreleaser-action: v6.4.0 -> v7.0.0
- docker/login-action: v3.6.0 -> v3.7.0
- ivuorinen/actions: v2026.01.21 -> v2026.02.24

* fix: address code review feedback

- Fix issue template YAML frontmatter (replace underscore separators
  with proper --- delimiters); exclude templates from mdformat
- Replace string(rune(n)) with strconv.Itoa(n) in test files to produce
  deterministic numeric directory names instead of Unicode characters
- Remove stale `make dev-deps` reference in README, replace with
  `make dev-setup`
- Extract ban/unban format strings into shared.MetricsFmtBanOperations
  and shared.MetricsFmtUnbanOperations constants
- Replace hardcoded coverage percentages in README with evergreen
  phrasing

* fix: address round 2 code review feedback for PR #120

- Fix corrupted path traversal example in docs/security.md
- Fix Renovate .mk regex to match nested paths (.*\.mk$)
- Update checkmake pre-commit hook to v0.3.2 to match Makefile
- Add sync.WaitGroup to unsynchronized goroutines in security tests
- Fix fmt-md target to use pre-commit run mdformat
- Pin markdownlint-cli2 to v0.21.0 in lint-md target
- Standardize //nolint:gosec to // #nosec annotations for gosec CLI

* fix(ci): install PyYAML dependency for PR lint workflow

The pr-lint workflow uses ivuorinen/actions/pr-lint which internally
calls validate-inputs running a Python script that imports yaml.
Python was set up but PyYAML was never installed, causing
ModuleNotFoundError at runtime.

* fix: address round 3 code review feedback for PR #120

- Wrap Windows-style path traversal example in backtick code span so
  backslashes render literally in docs/security.md
- Add Renovate-managed MARKDOWNLINT_CLI2_VERSION variable in Makefile
  to match the pattern used by all other tool versions

cmd/metrics_cmd.go

@@ -52,46 +52,44 @@ func printMetricsPlain(output io.Writer, snapshot MetricsSnapshot) error {
 
 	// System metrics
 	sb.WriteString("System:\n")
-	sb.WriteString(fmt.Sprintf("  Uptime: %ds\n", snapshot.UptimeSeconds))
-	sb.WriteString(fmt.Sprintf("  Max Memory: %.2f MB\n", float64(snapshot.MaxMemoryUsage)/(1024*1024)))
-	sb.WriteString(fmt.Sprintf("  Goroutines: %d\n\n", snapshot.GoroutineCount))
+	fmt.Fprintf(&sb, "  Uptime: %ds\n", snapshot.UptimeSeconds)
+	fmt.Fprintf(&sb, "  Max Memory: %.2f MB\n", float64(snapshot.MaxMemoryUsage)/(1024*1024))
+	fmt.Fprintf(&sb, "  Goroutines: %d\n\n", snapshot.GoroutineCount)
 
 	// Command metrics
 	sb.WriteString("Commands:\n")
-	sb.WriteString(fmt.Sprintf(shared.MetricsFmtTotalExecutions, snapshot.CommandExecutions))
-	sb.WriteString(fmt.Sprintf(shared.MetricsFmtTotalFailures, snapshot.CommandFailures))
+	fmt.Fprintf(&sb, shared.MetricsFmtTotalExecutions, snapshot.CommandExecutions)
+	fmt.Fprintf(&sb, shared.MetricsFmtTotalFailures, snapshot.CommandFailures)
 	if snapshot.CommandExecutions > 0 {
 		avgLatency := float64(snapshot.CommandTotalDuration) / float64(snapshot.CommandExecutions)
-		sb.WriteString(fmt.Sprintf(shared.MetricsFmtAverageLatencyTop, avgLatency))
+		fmt.Fprintf(&sb, shared.MetricsFmtAverageLatencyTop, avgLatency)
 	}
 	sb.WriteString("\n")
 
 	// Ban/Unban metrics
 	sb.WriteString("Ban Operations:\n")
-	sb.WriteString(fmt.Sprintf("  Ban Operations: %d (failures: %d)\n", snapshot.BanOperations, snapshot.BanFailures))
-	sb.WriteString(
-		fmt.Sprintf("  Unban Operations: %d (failures: %d)\n", snapshot.UnbanOperations, snapshot.UnbanFailures),
-	)
+	fmt.Fprintf(&sb, shared.MetricsFmtBanOperations, snapshot.BanOperations, snapshot.BanFailures)
+	fmt.Fprintf(&sb, shared.MetricsFmtUnbanOperations, snapshot.UnbanOperations, snapshot.UnbanFailures)
 	sb.WriteString("\n")
 
 	// Client metrics
 	sb.WriteString("Client Operations:\n")
-	sb.WriteString(fmt.Sprintf(shared.MetricsFmtTotalOperations, snapshot.ClientOperations))
-	sb.WriteString(fmt.Sprintf(shared.MetricsFmtTotalFailures, snapshot.ClientFailures))
+	fmt.Fprintf(&sb, shared.MetricsFmtTotalOperations, snapshot.ClientOperations)
+	fmt.Fprintf(&sb, shared.MetricsFmtTotalFailures, snapshot.ClientFailures)
 	if snapshot.ClientOperations > 0 {
 		avgLatency := float64(snapshot.ClientTotalDuration) / float64(snapshot.ClientOperations)
-		sb.WriteString(fmt.Sprintf(shared.MetricsFmtAverageLatencyTop, avgLatency))
+		fmt.Fprintf(&sb, shared.MetricsFmtAverageLatencyTop, avgLatency)
 	}
 	sb.WriteString("\n")
 
 	// Validation metrics
 	sb.WriteString("Validation:\n")
-	sb.WriteString(fmt.Sprintf("  Cache Hits: %d\n", snapshot.ValidationCacheHits))
-	sb.WriteString(fmt.Sprintf("  Cache Misses: %d\n", snapshot.ValidationCacheMiss))
-	sb.WriteString(fmt.Sprintf("  Failures: %d\n", snapshot.ValidationFailures))
+	fmt.Fprintf(&sb, "  Cache Hits: %d\n", snapshot.ValidationCacheHits)
+	fmt.Fprintf(&sb, "  Cache Misses: %d\n", snapshot.ValidationCacheMiss)
+	fmt.Fprintf(&sb, "  Failures: %d\n", snapshot.ValidationFailures)
 	if total := snapshot.ValidationCacheHits + snapshot.ValidationCacheMiss; total > 0 {
 		hitRate := float64(snapshot.ValidationCacheHits) / float64(total) * 100
-		sb.WriteString(fmt.Sprintf("  Cache Hit Rate: %.2f%%\n", hitRate))
+		fmt.Fprintf(&sb, "  Cache Hit Rate: %.2f%%\n", hitRate)
 	}
 	sb.WriteString("\n")