Add update-task-v2 endpoint with tight execute loop and reduce log verbosity

[v1r3n]

Summary

• Update Task V2 endpoint: Added update_task_v2 to both TaskResourceApi (sync) and AsyncTaskResourceApi (async), calling POST /tasks/update-v2 which combines task update + poll into a single HTTP call, returning
  the next task to process
• Tight execute loop: __execute_and_update_task now loops (execute → update_v2 → get next task → execute → ...) instead of returning after a single task, reducing poll overhead and latency
• Async task completion: When an async task completes, the v2 response's next task is submitted back to the executor thread pool
• Log verbosity: Moved verbose task registration logs (banners, schema details, TaskDef field listings, "View at" URLs) from INFO to DEBUG — only final registration outcomes remain at INFO
• Process termination safety: TaskHandler now guards against terminating processes that were never started or already stopped
• Auth failure reset: Reset auth failure counter on any successful HTTP poll response, not just when tasks are returned
• Removed dead code: Deleted unused __poll_task single-task poll method (superseded by batch polling)
• Package setup: Added pythonpath to pytest config, added extend_path to conductor/init.py for namespace package support

Test plan

• Run unit tests for TaskRunner, AsyncTaskRunner, and TaskHandler — verify updated mock expectations for update_task_v2
• Integration test: start workers, verify tight loop processes consecutive tasks without re-polling
• Integration test: verify 204 (no next task) breaks the loop gracefully
• Verify INFO logs on startup are concise; enable DEBUG to see full registration details
• Test async worker completion path — confirm next task from v2 is picked up