feat(hooks): add todo-description-override hook to enforce atomic todo format

Override TodoWrite description via tool.definition hook to require
WHERE/WHY/HOW/RESULT in each todo title and enforce 1-3 tool call
granularity.

src/hooks/todo-description-override/description.ts

@@ -0,0 +1,28 @@
+export const TODOWRITE_DESCRIPTION = `Use this tool to create and manage a structured task list for tracking progress on multi-step work.
+
+## Todo Format (MANDATORY)
+
+Each todo title MUST encode four elements: WHERE, WHY, HOW, and EXPECTED RESULT.
+
+Format: "[WHERE] [HOW] to [WHY] — expect [RESULT]"
+
+GOOD:
+- "src/utils/validation.ts: Add validateEmail() for input sanitization — returns boolean"
+- "UserService.create(): Call validateEmail() before DB insert — rejects invalid emails with 400"
+- "validation.test.ts: Add test for missing @ sign — expect validateEmail('foo') to return false"
+
+BAD:
+- "Implement email validation" (where? how? what result?)
+- "Add dark mode" (this is a feature, not a todo)
+- "Fix auth" (what file? what changes? what's expected?)
+
+## Granularity Rules
+
+Each todo MUST be a single atomic action completable in 1-3 tool calls. If it needs more, split it.
+
+**Size test**: Can you complete this todo by editing one file or running one command? If not, it's too big.
+
+## Task Management
+- One in_progress at a time. Complete it before starting the next.
+- Mark completed immediately after finishing each item.
+- Skip this tool for single trivial tasks (one-step, obvious action).`