Refactor to cnotes: focused git notes tool

BREAKING CHANGE: Complete restructure from hooks to cnotes

Major Changes:
- Removed all hook handler code except git commit detection
- Simplified to focused git notes functionality only
- Renamed binary from 'hooks' to 'cnotes'
- Restructured CLI: cnotes (hook handler), cnotes show, cnotes install, etc.
- Updated module path to github.com/imjasonh/cnotes
- Rewrote README and CLAUDE.md for new focused scope

New Command Structure:
- cnotes           # Main hook handler (receives Claude Code calls)
- cnotes show      # Pretty-print conversation notes
- cnotes install   # Configure Claude Code to use cnotes
- cnotes backup    # Backup conversation notes
- cnotes restore   # Restore notes from backup
- cnotes list      # List commits with notes

This creates a much cleaner, focused tool specifically for git conversation notes.

cmd/notes.go

@@ -6,16 +6,10 @@ import (
 	"os/exec"
 	"strings"
 
-	"github.com/imjasonh/hooks/internal/notes"
+	"github.com/imjasonh/cnotes/internal/notes"
 	"github.com/spf13/cobra"
 )
 
-var notesCmd = &cobra.Command{
-	Use:   "notes",
-	Short: "Manage git notes backups and restoration",
-	Long:  `Commands for backing up, restoring, and managing Claude conversation notes.`,
-}
-
 var backupCmd = &cobra.Command{
 	Use:   "backup [filename]",
 	Short: "Backup all conversation notes to a JSON file",
@@ -209,9 +203,8 @@ func getCommitInfo(commit string) string {
 }
 
 func init() {
-	rootCmd.AddCommand(notesCmd)
-	notesCmd.AddCommand(backupCmd)
-	notesCmd.AddCommand(restoreCmd)
-	notesCmd.AddCommand(showCmd)
-	notesCmd.AddCommand(listCmd)
+	rootCmd.AddCommand(backupCmd)
+	rootCmd.AddCommand(restoreCmd)
+	rootCmd.AddCommand(showCmd)
+	rootCmd.AddCommand(listCmd)
 }