feat(07-05): implement keyhunter hook install/uninstall with embedded pre-commit script

- cmd/hook.go: install/uninstall subcommands with --force flag
- cmd/hook_script.sh: embedded via go:embed, runs keyhunter scan on staged files
- KEYHUNTER-HOOK v1 marker prevents accidental deletion of non-owned hooks
- Backup existing hooks on --force install
- cmd/hook_test.go: 10 tests covering fresh install, non-repo, force/backup, overwrite, uninstall lifecycle
- Remove hookCmd stub from cmd/stubs.go

cmd/stubs.go

@@ -21,12 +21,6 @@ var verifyCmd = &cobra.Command{
 	RunE:  notImplemented("verify", "Phase 5"),
 }
 
-var importCmd = &cobra.Command{
-	Use:   "import",
-	Short: "Import findings from TruffleHog or Gitleaks output (Phase 7)",
-	RunE:  notImplemented("import", "Phase 7"),
-}
-
 var reconCmd = &cobra.Command{
 	Use:   "recon",
 	Short: "Run OSINT recon across internet sources (Phase 9+)",
@@ -47,12 +41,6 @@ var dorksCmd = &cobra.Command{
 	RunE:  notImplemented("dorks", "Phase 8"),
 }
 
-var hookCmd = &cobra.Command{
-	Use:   "hook",
-	Short: "Install or manage git pre-commit hooks (Phase 7)",
-	RunE:  notImplemented("hook", "Phase 7"),
-}
-
 var scheduleCmd = &cobra.Command{
 	Use:   "schedule",
 	Short: "Manage scheduled recurring scans (Phase 17)",