WIP: Add hook API for dynamic tool control with plan-mode hook example

- Add pi.getTools() and pi.setTools(toolNames) to HookAPI
- Hooks can now enable/disable tools dynamically
- Changes take effect on next agent turn

New example hook: plan-mode.ts
- Claude Code-style read-only exploration mode
- /plan command toggles plan mode on/off
- Plan mode tools: read, bash, grep, find, ls
- Edit/write tools disabled in plan mode
- Injects context telling agent about restrictions
- After each response, prompts to execute/stay/refine
- State persists across sessions

packages/coding-agent/src/modes/rpc/rpc-mode.ts

@@ -189,6 +189,8 @@ export async function runRpcMode(session: AgentSession): Promise<never> {
 			appendEntryHandler: (customType, data) => {
 				session.sessionManager.appendCustomEntry(customType, data);
 			},
+			getToolsHandler: () => session.getActiveToolNames(),
+			setToolsHandler: (toolNames) => session.setActiveToolsByName(toolNames),
 			uiContext: createHookUIContext(),
 			hasUI: false,
 		});