Move POST /api/jobs/:id/survey/analyze off the FastAPI worker thread
by routing it through the LLM task queue (same pattern as cover_letter,
company_research, resume_optimize).
- Extract prompt builders + run_survey_analyze() to scripts/survey_assistant.py
- Add survey_analyze to LLM_TASK_TYPES (task_scheduler.py) with 2.5 GB VRAM budget
(text mode: phi3:mini; visual mode uses vision service's own VRAM pool)
- Add elif branch in task_runner._run_task; result stored as JSON in error col
- Replace sync endpoint body with submit_task(); add GET /survey/analyze/task poll
- Update survey.ts store: analyze() now fires task + polls at 3s interval;
silently attaches to existing in-flight task when is_new=false
- SurveyView button label shows task stage while polling
Fixes load-test spike: ~22 greenlets blocking on LLM inference at 100 concurrent
users, causing 90s poll timeouts on cover_letter and research tasks.
