feat(webhook): hermes webhook CLI + skill for event-driven subscriptions (#3578)

Adds 'hermes webhook' CLI subcommand and a skill — zero new model tools.

CLI commands (require webhook platform to be enabled):
  hermes webhook subscribe <name> [--events, --prompt, --deliver, ...]
  hermes webhook list
  hermes webhook remove <name>
  hermes webhook test <name>

All commands gate on webhook platform being enabled in config. If not
configured, prints setup instructions (gateway setup wizard, manual
config.yaml, or env vars).

The agent uses these via terminal tool, guided by the webhook-subscriptions
skill which documents setup, common patterns (GitHub, Stripe, CI/CD,
monitoring), prompt template syntax, security, and troubleshooting.

Adapter enhancement: webhook.py hot-reloads dynamic subscriptions from
~/.hermes/webhook_subscriptions.json on each incoming request (mtime-gated).
Static config.yaml routes always take precedence.

Docs: updated webhooks.md with Dynamic Subscriptions section, added
hermes webhook to cli-commands.md reference.

No new model tools. No toolset changes.

24 new tests for CLI CRUD, persistence, enabled-gate, and adapter
dynamic route loading.

hermes_cli/main.py

@@ -2339,6 +2339,12 @@ def cmd_cron(args):
     cron_command(args)
 
 
+def cmd_webhook(args):
+    """Webhook subscription management."""
+    from hermes_cli.webhook import webhook_command
+    webhook_command(args)
+
+
 def cmd_doctor(args):
     """Check configuration and dependencies."""
     from hermes_cli.doctor import run_doctor
@@ -3523,7 +3529,38 @@ For more help on a command:
     cron_subparsers.add_parser("tick", help="Run due jobs once and exit")
 
     cron_parser.set_defaults(func=cmd_cron)
-    
+
+    # =========================================================================
+    # webhook command
+    # =========================================================================
+    webhook_parser = subparsers.add_parser(
+        "webhook",
+        help="Manage dynamic webhook subscriptions",
+        description="Create, list, and remove webhook subscriptions for event-driven agent activation",
+    )
+    webhook_subparsers = webhook_parser.add_subparsers(dest="webhook_action")
+
+    wh_sub = webhook_subparsers.add_parser("subscribe", aliases=["add"], help="Create a webhook subscription")
+    wh_sub.add_argument("name", help="Route name (used in URL: /webhooks/<name>)")
+    wh_sub.add_argument("--prompt", default="", help="Prompt template with {dot.notation} payload refs")
+    wh_sub.add_argument("--events", default="", help="Comma-separated event types to accept")
+    wh_sub.add_argument("--description", default="", help="What this subscription does")
+    wh_sub.add_argument("--skills", default="", help="Comma-separated skill names to load")
+    wh_sub.add_argument("--deliver", default="log", help="Delivery target: log, telegram, discord, slack, etc.")
+    wh_sub.add_argument("--deliver-chat-id", default="", help="Target chat ID for cross-platform delivery")
+    wh_sub.add_argument("--secret", default="", help="HMAC secret (auto-generated if omitted)")
+
+    webhook_subparsers.add_parser("list", aliases=["ls"], help="List all dynamic subscriptions")
+
+    wh_rm = webhook_subparsers.add_parser("remove", aliases=["rm"], help="Remove a subscription")
+    wh_rm.add_argument("name", help="Subscription name to remove")
+
+    wh_test = webhook_subparsers.add_parser("test", help="Send a test POST to a webhook route")
+    wh_test.add_argument("name", help="Subscription name to test")
+    wh_test.add_argument("--payload", default="", help="JSON payload to send (default: test payload)")
+
+    webhook_parser.set_defaults(func=cmd_webhook)
+
     # =========================================================================
     # doctor command
     # =========================================================================