refactor: remove todo tool (#35989)

packages/opencode/specs/effect/tools.md

@@ -50,7 +50,6 @@ These exported tool definitions currently use `Tool.define(...)` in `src/tool`:
 - [x] `read.ts`
 - [x] `skill.ts`
 - [x] `task.ts`
-- [x] `todo.ts`
 - [x] `webfetch.ts`
 - [x] `websearch.ts`
 - [x] `write.ts`

packages/opencode/specs/tui-plugins.md

@@ -381,7 +381,6 @@ Mode pushes are automatically tracked by the plugin runtime. If a plugin is disa
   - `vcs?.branch`
   - `session.count()`
   - `session.diff(sessionID)`
-  - `session.todo(sessionID)`
   - `session.messages(sessionID)`
   - `session.status(sessionID)`
   - `session.permission(sessionID)`
@@ -511,12 +510,11 @@ Metadata is persisted by plugin id.
 - `internal:sidebar-context`
 - `internal:sidebar-mcp`
 - `internal:sidebar-lsp`
-- `internal:sidebar-todo`
 - `internal:sidebar-files`
 - `internal:sidebar-footer`
 - `internal:plugin-manager`
 
-Sidebar content order is currently: context `100`, mcp `200`, lsp `300`, todo `400`, files `500`.
+Sidebar content order is currently: context `100`, mcp `200`, lsp `300`, files `500`.
 
 The plugin manager is exposed as a command with title `Plugins` and value `plugins.list`.