feat(scrape): vision OCR of image-only doc pages (support matrices)

Some HPE pages carry information only inside an image. The Morpheus
release schedule / support-lifecycle matrix (sf000111242en_us) is the
case that surfaced this: the entire "which version ships when, when a
stream hits Maintenance/EOL" table is a JPEG, so html_to_md dropped
every value and retrieval could never answer "when does 8.x.x reach
end of life".

New scrape/vision.py (opt-in via VISION_OCR) transcribes qualifying
images with a local Ollama vision model and appends a labeled markdown
block to the page so the text is chunked, embedded and retrieved.

Model/prompt chosen against ground truth on the matrix (14x4 cells):
- qwen2.5vl:7b + a bare "transcribe the table" prompt: 55-56/56, ~18s,
  GPU-resident, and prompt-ROBUST (accurate without hand-tuning).
- gemma3:12b needs an exact "read row by row, keep cells aligned"
  prompt or it shifts a column by one row; qwen2.5vl:32b is no more
  accurate and 5x slower (CPU spill). Both documented in the code.
- Note: self-consistency (2 samples must agree) only catches RANDOM
  flakiness — a wrong read is stable across seeds — so every block also
  ships a "verify against the source image" caveat.

Reliability/cost:
- content-hash cache in corpus/.vision-cache/ (committed) — each unique
  image OCR'd once ever, shared across version bundles.
- VISION_MAX_NEW bounds NEW OCRs per run so the first pass can't balloon
  into hours; the cache fills incrementally. Deferred count is logged.
- every failure path degrades to the pre-vision behavior; never blocks
  the scrape.

Also:
- add the morpheus_release_schedule bundle (sf single-doc) + 2 eval
  golden queries for it.
- fetch_single_doc: title falls back to the bundle title (not docId)
  when a page has no <h1> (sf solution articles).
- Pillow in requirements-vision.txt (scrape-only; kept out of the
  server image), installed + VISION_* wired into refresh.yml.

Verified locally: matrix transcribes to the exact 14-row table; second
run is a cache hit (ocr=0).

Co-Authored-By: Claude Opus 4.8 <[email protected]>
Claude-Session: https://claude.ai/code/session_01LFowQzJu7k97QLCRDSAeh1

bundles.json

@@ -149,5 +149,22 @@
     "dates": {},
     "landing_page": "a50009231enw",
     "source_url": "https://www.hpe.com/psnow/doc/a50009231enw"
+  },
+  {
+    "slug": "morpheus_release_schedule",
+    "doc_id": "sf000111242en_us",
+    "title": "HPE Morpheus Software Release Schedule",
+    "version": null,
+    "platform": null,
+    "product": "Release Schedule",
+    "language": "en-US",
+    "page_count": 1,
+    "mode": "single",
+    "abstract": "",
+    "dates": {
+      "Published": ""
+    },
+    "landing_page": "sf000111242en_us",
+    "source_url": "https://support.hpe.com/hpesc/public/docDisplay?docId=sf000111242en_us"
   }
 ]