fix(legal-aid): render PDF pages as JPEG q85 instead of PNG

Bundling all report pages as 180-DPI PNG base64 in one ai-gateway
chat-completions request blew past its body limit and returned 413.
A rendered table page is mostly white, so q85 JPEG is several times
smaller while keeping the table text crisp enough for Claude Vision.
Pairs with the ai-gateway limit bump to 25mb.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

api/routes/legal_aid.py

@@ -123,8 +123,12 @@ async def parse_pdf_report(
             page_count = min(len(doc), _PDF_MAX_PAGES)
             for i in range(page_count):
                 pix = doc[i].get_pixmap(dpi=_PDF_RENDER_DPI)
-                png = pix.tobytes("png")
-                images_b64.append(("image/png", base64.b64encode(png).decode("ascii")))
+                # JPEG (not PNG): a rendered table page is mostly white, and
+                # PNG of it is several × larger than a q85 JPEG. Bundling all
+                # pages as PNG blew past ai-gateway's body limit (413). JPEG
+                # q85 keeps the table text crisp enough for Claude Vision.
+                jpg = pix.tobytes("jpeg", jpg_quality=85)
+                images_b64.append(("image/jpeg", base64.b64encode(jpg).decode("ascii")))
     except Exception as e:
         logger.exception("Legal Aid PDF render failed")
         raise HTTPException(status_code=422, detail=f"PDF render error: {e}")