Fix clipped receipt margins, add time-of-day naming, speed up rotation detection

- vision/document.py: pad_quad() expands the detected quad outward
  before warping so a straight-line contour fit doesn't clip the first
  character of every line on a slightly curled/wrinkled receipt
- ocr/extract.py + llm/vision.py: extract transaction time (HH:MM) so
  same-day repeat visits to a vendor get distinct filenames
  (2023-03-20_1525_walmart.pdf vs. a later same-day trip)
- vision/orient.py: downscale before Tesseract OSD/confidence-sweep
  rotation detection — this was the dominant cost in the detection
  phase (7x speedup: 472s -> 67s on a 36s test video)

paperpod/naming/filename.py

@@ -27,6 +27,9 @@ class NamingResult:
     source: str  # "ocr" | "none" (will include "speech" once module 4 exists)
 
 
+_TIME_RE = re.compile(r"^([01]\d|2[0-3]):([0-5]\d)$")
+
+
 def build_name(
     date: str | None,
     vendor: str | None,
@@ -35,11 +38,21 @@ def build_name(
     form_code: str | None = None,
     tax_year: str | None = None,
     org_name: str | None = None,
+    time: str | None = None,
 ) -> NamingResult:
-    """date must already be normalized to YYYY-MM-DD, or None."""
+    """date must already be normalized to YYYY-MM-DD, time to HH:MM, or None.
+
+    Time is appended to the date (e.g. 2023-03-20_1525) whenever it was
+    extracted, so two same-day visits to the same vendor (Walmart in the
+    morning and again in the evening) don't collide or silently overwrite.
+    """
     vendor_slug = slugify(vendor, max_vendor_len) if vendor else None
     ts = fallback_dt.strftime("%Y%m%d_%H%M%S")
 
+    date_part = date
+    if date and time and _TIME_RE.match(time):
+        date_part = f"{date}_{time.replace(':', '')}"
+
     # Tax slips: prefer 2023_T4_York_University over UNSORTED_t4_york_university_<timestamp>.
     if form_code:
         org_slug = slugify(org_name, max_vendor_len) if org_name else None
@@ -58,10 +71,10 @@ def build_name(
             return NamingResult(stem=f"{code}_{org_slug}", source="ocr")
         return NamingResult(stem=code.lower(), source="ocr")
 
-    if date and vendor_slug:
-        return NamingResult(stem=f"{date}_{vendor_slug}", source="ocr")
-    if date:
-        return NamingResult(stem=f"{date}_UNSORTED", source="ocr")
+    if date_part and vendor_slug:
+        return NamingResult(stem=f"{date_part}_{vendor_slug}", source="ocr")
+    if date_part:
+        return NamingResult(stem=f"{date_part}_UNSORTED", source="ocr")
     if vendor_slug:
         return NamingResult(stem=f"UNSORTED_{vendor_slug}_{ts}", source="ocr")
     return NamingResult(stem=f"UNSORTED_{ts}", source="none")