FN-6107: always summarize untitled agent-created tasks

Ensure agent-created untitled tasks still request AI-generated titles even when project auto-summarization is disabled.

- force summarize=true for agent-created tasks that do not provide an explicit title
- add engine tests covering untitled, titled, and title-generation behavior with autoSummarizeTitles disabled
- document the agent-task summarization behavior in settings docs
- add a patch changeset for the published CLI package

Files changed:
 .changeset/agent-task-title-summaries.md          |  5 ++
 docs/settings-reference.md                        |  2 +-
 packages/engine/src/__tests__/agent-tools.test.ts | 63 +++++++++++++++++++++++
 packages/engine/src/agent-tools.ts                |  1 +
 4 files changed, 70 insertions(+), 1 deletion(-)

Fusion-Task-Id: FN-6107

Fusion-Task-Lineage: d0c25981-a5cb-48ca-b835-9267817b4edd

.changeset/agent-task-title-summaries.md

@@ -0,0 +1,5 @@
+---
+"@runfusion/fusion": patch
+---
+
+Agent-created tasks without explicit titles now request AI title summarization regardless of the project auto-summarize setting.