mcs150: enrich intake from FMCSA carrier census before PDF fill

The MCS-150 biennial update re-confirms the carrier's existing FMCSA
record. Previously the PDF filler only had whatever the intake form
collected; rescued/sparse orders (or orders where the carrier's data
lives in FMCSA, not the intake) produced near-empty forms. Now we pull
the carrier census (legal name, address, EIN, fleet counts) from the
FMCSA carrier API and merge it under any customer-provided intake values
(customer edits win), so the form is pre-filled with the carrier's
current registered data. Refactored the FMCSA fetch into a shared
_fetch_fmcsa_carrier helper used by both enrichment and status check.

scripts/document_gen/templates/diag_mcs150.py

@@ -0,0 +1,55 @@
+"""Diagnostic: inspect the actual MCS-150 fill output.
+Reports, per page: the AcroForm fields present (name + value + rect), and the
+rendered text, so we can see WHERE data lands vs WHERE the blank/example fields
+are. Run in the workers container against the live template + a fresh fill.
+"""
+import sys, json
+sys.path.insert(0, "/app")
+from pypdf import PdfReader
+
+TEMPLATE = "/app/docs/MCS-150 Form.pdf"
+
+
+def field_rows(reader, label):
+    print(f"\n===== {label} =====")
+    for i, pg in enumerate(reader.pages):
+        annots = pg.get("/Annots")
+        if not annots:
+            continue
+        annots = annots.get_object() if hasattr(annots, "get_object") else annots
+        rows = []
+        for a in annots:
+            o = a.get_object()
+            t = o.get("/T")
+            if t is None and o.get("/Parent"):
+                t = o["/Parent"].get_object().get("/T")
+            v = o.get("/V")
+            rect = o.get("/Rect")
+            ft = o.get("/FT")
+            if t:
+                rows.append((str(t), str(ft), str(v) if v is not None else "", [round(float(x)) for x in rect] if rect else None))
+        if rows:
+            print(f"-- PDF page {i+1} ({len(rows)} fields) --")
+            for name, ft, val, rect in rows:
+                vstr = f" = {val!r}" if val else ""
+                print(f"    {name} [{ft}]{vstr}  rect={rect}")
+
+
+# 1) the template as-is — what fields + any example values?
+r = PdfReader(TEMPLATE)
+field_rows(r, "TEMPLATE (original)")
+
+# 2) a fresh fill
+from scripts.document_gen.templates.mcs150_pdf_filler import fill_mcs150
+intake = {
+    "dot_number": "1609564", "legal_name": "MITCHELL W ALLEN",
+    "dba_name": "", "entity_type": "sole_proprietorship",
+    "business_street": "123 Main St", "business_city": "Town",
+    "business_state": "TX", "business_zip": "75001",
+    "phone": "5125551234", "ein": "123456789",
+    "signer_name": "Mitchell W Allen", "signer_title": "Owner",
+    "power_units": "2", "drivers": "1",
+}
+p = fill_mcs150(intake, order_number="DIAG")
+print("\nfilled file:", p)
+field_rows(PdfReader(p), "FILLED")