feat(event_bus): wire webhooks, channels & skills through the event bus (#379)

* feat(event_bus): enhance domain event handling across modules

- Added new `DomainEvent` variants for channel and skill events, including `ChannelMessageReceived`, `ChannelMessageProcessed`, `ChannelConnected`, `ChannelDisconnected`, `SkillLoaded`, `SkillStopped`, and `SkillStartFailed`.
- Implemented event publishing in the channels and skills modules to track message processing and skill lifecycle events.
- Created dedicated event bus handler files for the skills and webhooks domains, preparing for future subscriber implementations.
- Updated documentation in `CLAUDE.md` to reflect the new domain events and their usage.

These changes improve the observability and modularity of the system by leveraging an event-driven architecture for cross-module communication.

* feat(event_bus): implement channel and webhook event handling

- Introduced `ChannelInboundSubscriber` to handle inbound channel messages, triggering the agent inference loop and sending replies via the backend REST API.
- Added `WebhookRequestSubscriber` to manage incoming webhook requests, routing them to the appropriate skill and handling responses.
- Updated the global event bus initialization in `bootstrap_skill_runtime` to register both channel and webhook subscribers.
- Enhanced `DomainEvent` with new variants for channel inbound messages and webhook requests, improving event-driven communication across modules.

These changes enhance the modularity and responsiveness of the system by leveraging an event-driven architecture for channel and webhook interactions.

* refactor(event_bus): update domain event documentation and subscriber initialization

- Revised the documentation in `CLAUDE.md` to provide a concise overview of domain events and their associated subscriber files, enhancing clarity for future development.
- Updated the `start_channels` function to initialize `WebhookRequestSubscriber` and `ChannelInboundSubscriber`, ensuring proper event handling for webhooks and channel messages.
- Streamlined the event bus subscriber registration process, reinforcing the modular architecture of the system.

These changes improve the maintainability and usability of the event bus framework, facilitating better cross-module communication.

* style: apply cargo fmt formatting

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix(event_bus): remove duplicate subscriber registration in start_channels

WebhookRequestSubscriber and ChannelInboundSubscriber were registered in
both bootstrap_skill_runtime() and start_channels(), causing events to
be handled twice when both paths run in the same process.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix(event_bus): prevent subscriber handles from being dropped on function exit

SubscriptionHandle::drop aborts the background task. Since
bootstrap_skill_runtime() returns immediately after setup, the local
handles were dropped, cancelling both subscribers. Use std::mem::forget
to leak the handles so the tasks live for the entire process.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix(event_bus): ensure subscriber handles persist beyond function exit

Modified the handling of subscriber registration to prevent premature dropping of handles in `bootstrap_skill_runtime()`. This change ensures that the background tasks for subscribers remain active for the entire process lifecycle, enhancing event handling reliability.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix(webhooks): use proper JSON serialization for error response bodies

Hand-escaped JSON strings only handled double quotes, not backslashes,
newlines, or other control chars. Replaced with serde_json serialization
via an error_body() helper.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix(webhooks): use proper JSON serialization for error response bodies

Hand-escaped JSON strings only handled double quotes, not backslashes,
newlines, or other control chars. Replaced with serde_json serialization
via an error_body() helper.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/core/jsonrpc.rs

@@ -689,6 +689,22 @@ pub async fn bootstrap_skill_runtime() {
     let _ = std::fs::create_dir_all(&workspace_dir);
     engine.set_workspace_dir(workspace_dir);
 
+    // --- Event bus bootstrap ---
+    // Ensure the global event bus is initialized (no-op if already done by start_channels).
+    let bus =
+        crate::openhuman::event_bus::init_global(crate::openhuman::event_bus::DEFAULT_CAPACITY);
+    // Register domain subscribers for cross-module event handling.
+    // Leak the handles so the background tasks live for the entire process —
+    // SubscriptionHandle::drop aborts the task, and bootstrap_skill_runtime()
+    // returns immediately after setup.
+    std::mem::forget(bus.subscribe(Arc::new(
+        crate::openhuman::webhooks::bus::WebhookRequestSubscriber::new(),
+    )));
+    std::mem::forget(bus.subscribe(Arc::new(
+        crate::openhuman::channels::bus::ChannelInboundSubscriber::new(),
+    )));
+    log::info!("[event_bus] webhook and channel subscribers registered");
+
     // --- Socket manager bootstrap ---
     let socket_mgr = Arc::new(SocketManager::new());
     set_global_socket_manager(socket_mgr.clone());