Address PR feedback:

- Remove hardcoded git.fbrns.co server (users should add their own)
- Add comment about how to add servers
- Support --force flag in cmd_init to regenerate config file

This addresses han's review feedback:
1. Removed git.fbrns.co from default config
2. Config file can now be regenerated with --force flag
3. We continue using the existing config file (not separate file)

skills/kugetsu/scripts/kugetsu

@@ -793,7 +793,7 @@ cmd_init() {
 
     ensure_dirs
 
-    if [ ! -f "$KUGETSU_DIR/config" ]; then
+    if [ ! -f "$KUGETSU_DIR/config" ] || [ "$force" = true ]; then
         cat > "$KUGETSU_DIR/config" << 'EOF'
 # User configuration overrides
 # Values set here take precedence over defaults
@@ -804,9 +804,9 @@ cmd_init() {
 
 # Git server configurations
 # Format: GIT_SERVERS["hostname"]="https://hostname"
+# Add servers with: kugetsu server add <name> <url>
 declare -A GIT_SERVERS
 GIT_SERVERS["github.com"]="https://github.com"
-GIT_SERVERS["git.fbrns.co"]="https://git.fbrns.co"
 DEFAULT_GIT_SERVER="github.com"
 EOF
         echo "Created config file: $KUGETSU_DIR/config"