Matrix intake: main-timeline nudge, clearer messages, note text in grid

Four bot-side UX fixes surfaced by the live smoke:
- Post a brief pointer in the main timeline (a reply to the user's message)
  alongside the in-thread proposal card, so proposals aren't missed inside a
  thread. Pointer only — approvals still happen in the thread, where the note
  is visible (you can't make an informed yes/no without seeing it).
- A bare yes/no typed in the main timeline while a proposal is pending now
  gets a "reply in the thread" redirect instead of "couldn't tell what to record."
- Clearer commit confirmations: "Created a new grid entry for X" vs
  "Logged a note on X (existing grid entry)."
- Send a blank communication subject when a note is present so the grid's
  one-line note summary shows the note text, not the "(Matrix)" label
  (provenance stays in source="matrix_intake").

backend/matrix_intake/bot.py

@@ -31,10 +31,18 @@ async def main():
     client = AsyncClient(mx["homeserver"], mx["user_id"])
     client.restore_login(user_id=mx["user_id"], device_id=mx["device_id"], access_token=mx["token"])
     say = matrix_io.make_say(client)
+    nudge = matrix_io.make_reply(client)
     store = proposals.ProposalStore()
     intake_room = mx["intake_room"]
 
     async def handle_intake(room_id, root, text):
+        # A bare yes/no/approve typed in the MAIN timeline (not inside a proposal's thread) is
+        # an easy slip — point the user back to the thread rather than parse it as a new intake.
+        action, _ = proposals.interpret_reply(text)
+        if action in ("approve", "reject") and store.any_pending():
+            await nudge(room_id, "👉 To approve, reject, or edit a proposal, open its **thread** "
+                                 "and reply there — the note is in the thread.", root)
+            return
         try:
             proposal = await asyncio.to_thread(parse.parse_message, text)
         except Exception as exc:  # Spark/Qwen unreachable or bad response
@@ -56,6 +64,9 @@ async def main():
             pass
         store.put(root, proposal)
         await say(room_id, proposals.render(proposal) + hint, root)
+        # Also drop a brief, un-threaded reply in the main timeline so the proposal isn't
+        # easy to miss inside a thread (the full card + yes/edit/no stay in the thread).
+        await nudge(room_id, proposals.summary_line(proposal), root)
 
     async def handle_reply(room_id, root, text):
         action, payload = proposals.interpret_reply(text)