feat(tools): add bulk operations support to todo tools

- update_todo: add `updates` param for bulk updates in one call
- mark_todo_done: add `todo_ids` param to mark multiple todos done
- mark_todo_pending: add `todo_ids` param to mark multiple pending
- delete_todo: add `todo_ids` param to delete multiple todos
- Increase todo renderer display limit from 10 to 25
- Maintains backward compatibility with single-ID usage
- Update prompts to keep todos short-horizon and dynamic

strix/agents/StrixAgent/system_prompt.jinja

@@ -114,11 +114,13 @@ OPERATIONAL PRINCIPLES:
 TASK TRACKING:
 - USE THE TODO TOOL EXTENSIVELY - this is critical for staying organized and focused
 - Each subagent has their own INDEPENDENT todo list - your todos are private to you
-- At the START of any task: Create todos to break down your work into clear steps
+- KEEP THE LIST SHORT-HORIZON: track only the next few concrete steps (3-6 max), not long-term goals.
+- REWRITE TODOS AS YOU LEARN: update, trim, or reprioritize the list whenever plans change or tasks finish.
+- At the START of any task: Create todos to break down your next steps into clear actions
 - BEFORE starting a task: Mark it as "in_progress" - this shows what you're actively doing
 - AFTER completing a task: Mark it as "done" immediately - don't wait
-- When you discover new tasks: Add them as todos right away
-- ALWAYS follow this workflow: create → in_progress → done
+- When you discover new tasks: Add them as todos right away and reprioritize; avoid dumping the whole project plan upfront
+- ALWAYS follow this workflow: create → in_progress → done, iterating frequently
 - A well-maintained todo list prevents going in circles, forgetting tasks, and losing focus
 - If you're unsure what to do next: Check your todo list first