feat(cli): add hermes plugins install/remove/list command

Plugin management via git repos:
- hermes plugins install <git-url|owner/repo>
- hermes plugins update <name>
- hermes plugins remove <name> (aliases: rm, uninstall)
- hermes plugins list (alias: ls)

Security: path traversal protection, no shell injection, manifest
version guard, insecure URL warnings.

42 tests covering security, dispatch, helpers, and commands.

Based on work by Angello Picasso in PR #1785. Closes #1789.

hermes_cli/main.py

@@ -3529,6 +3529,46 @@ For more help on a command:
 
     skills_parser.set_defaults(func=cmd_skills)
 
+    # =========================================================================
+    # plugins command
+    # =========================================================================
+    plugins_parser = subparsers.add_parser(
+        "plugins",
+        help="Manage plugins — install, update, remove, list",
+        description="Install plugins from Git repositories, update, remove, or list them.",
+    )
+    plugins_subparsers = plugins_parser.add_subparsers(dest="plugins_action")
+
+    plugins_install = plugins_subparsers.add_parser(
+        "install", help="Install a plugin from a Git URL or owner/repo"
+    )
+    plugins_install.add_argument(
+        "identifier",
+        help="Git URL or owner/repo shorthand (e.g. anpicasso/hermes-plugin-chrome-profiles)",
+    )
+    plugins_install.add_argument(
+        "--force", "-f", action="store_true",
+        help="Remove existing plugin and reinstall",
+    )
+
+    plugins_update = plugins_subparsers.add_parser(
+        "update", help="Pull latest changes for an installed plugin"
+    )
+    plugins_update.add_argument("name", help="Plugin name to update")
+
+    plugins_remove = plugins_subparsers.add_parser(
+        "remove", aliases=["rm", "uninstall"], help="Remove an installed plugin"
+    )
+    plugins_remove.add_argument("name", help="Plugin directory name to remove")
+
+    plugins_subparsers.add_parser("list", aliases=["ls"], help="List installed plugins")
+
+    def cmd_plugins(args):
+        from hermes_cli.plugins_cmd import plugins_command
+        plugins_command(args)
+
+    plugins_parser.set_defaults(func=cmd_plugins)
+
     # =========================================================================
     # honcho command
     # =========================================================================