Improve documentation: README settings table, philosophy section, custom-tools intro, rpc hook_error event, hooks import aliases

packages/coding-agent/docs/rpc.md

@@ -559,6 +559,7 @@ Events are streamed to stdout as JSON lines during agent operation. Events do NO
 | `auto_compaction_end` | Auto-compaction completes |
 | `auto_retry_start` | Auto-retry begins (after transient error) |
 | `auto_retry_end` | Auto-retry completes (success or final failure) |
+| `hook_error` | Hook threw an error |
 
 ### agent_start
 
@@ -744,6 +745,19 @@ On final failure (max retries exceeded):
 }
 ```
 
+### hook_error
+
+Emitted when a hook throws an error.
+
+```json
+{
+  "type": "hook_error",
+  "hookPath": "/path/to/hook.ts",
+  "event": "tool_call",
+  "error": "Error message..."
+}
+```
+
 ## Error Handling
 
 Failed commands return a response with `success: false`: