v1.1.1 — Wire 5 gaps

Fixed

1. Context usage now live — /usage shows real token breakdown from session events, prompt shows budget indicators (⚠/🔴)
2. Delegate wired — /delegate <task> runs an isolated sub-agent prompt in a separate session
3. StubTool cleaned — moved from production tool_policy.rs to test module
4. Checkpoints persisted — saved to .zavora/checkpoints.json, survives CLI restarts
5. todo_list agent tool — model can now create/complete/view/list/delete todos during execution

157 tests, 0 failures, 0 warnings.

What's Changed

• fix: wire 5 gaps — context usage, delegate, StubTool, checkpoint persistence, todo tool by @jkmaina in #60

Full Changelog: v1.1.0...v1.1.1