feat(keyword-detector): handle ultrawork keyword after greeting patterns

- Add TRAILING_GREETING_ULTRAWORK_PATTERN to detect 'hi ultrawork' style inputs
- Rename hasLeadingUltraworkKeyword to hasEdgeUltraworkKeyword for clarity
- Add extractUltraworkTask guard to return empty string for greeting-only inputs
- Add comprehensive test coverage for edge trigger scenarios

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/hooks/.sisyphus/ralph-loop.local.md

@@ -0,0 +1,12 @@
+---
+active: true
+iteration: 2
+max_iterations: 100
+completion_promise: "DONE"
+initial_completion_promise: "DONE"
+started_at: "2026-03-14T04:20:58.486Z"
+session_id: "new-session-1"
+strategy: "reset"
+message_count_at_start: 0
+---
+Build feature