🤖 fix: enforce task status transitions

[ammar-agent]

Implements a small status-transition state machine for agent tasks:

• Centralizes taskStatus writes in TaskService.setTaskStatus with allowed transitions (queued|running|awaiting_report|reported)
• Ensures invariants:
  • Clears taskPrompt once a task leaves queued
  • Stamps reportedAt when entering reported
• Replaces direct config writes of taskStatus="reported" with the transition helper
• Adds unit tests for invalid transitions + reportedAt stamping

Validation:

• bun test src/node/services/taskService.test.ts
• make static-check

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Generated with mux • Model: openai:gpt-5.2 • Thinking: xhigh