Mobile Phase 8d: sort controls across Grid, Pipeline, Contacts

Add a shared SortPill + SortSheet (label+hint option rows) and per-surface sort
tables:
- Grid: Name / Pipeline stage / Committed / Last contact / Priority, applied in
  the displayed memo (name is the tiebreak; staleness ranks longest-since-contact
  first, no-activity treated as most stale; committed uses the fund rollup).
- Pipeline: Name / Amount / Last activity / Priority, sorted within each stage.
  "Last activity" uses opp.updated_at as a recency proxy until the Pipeline card
  wires true last-contact recency (8f).
- Contacts: drop the investor/prospect type tabs (the prospect type is unused);
  add a Priority sort alongside Name A-Z/Z-A and Last contact.

contact_grid_signals() now also surfaces the linked investor's priority flag,
injected on both contact read paths (same derive-on-read contract as committed /
pipeline_stage), powering the Contacts Priority sort. Extended
test_contacts_grid_signals.py covers it; 39/39 backend green.

backend/test_contacts_grid_signals.py

@@ -7,7 +7,8 @@ sourced from the fundraising grid (the canonical investor model), for the mobile
                     mirroring existing_investor_by_source_row (committed capital, not graveyard);
   - `pipeline_stage` -> that investor's live derived stage (drives the card's stage pill),
                     or null when the investor isn't in the pipeline.
-A contact with no grid link (pure classic/legacy contact) gets committed 0 / stage null.
+  - `priority` -> that investor's priority flag (drives the mobile Contacts Priority sort, 8d).
+A contact with no grid link (pure classic/legacy contact) gets committed 0 / stage null / priority false.
 Signals are derived fresh on read and never stored on the contact. Synthetic data only.
 
 Run: cd backend && python3 test_contacts_grid_signals.py
@@ -138,16 +139,27 @@ def main():
         check((vince or {}).get("pipeline_stage") is None,
               f"Vince.pipeline_stage is None (no grid link) (got {(vince or {}).get('pipeline_stage')!r})")
 
+        # ── priority signal: flagged investor → contact's Priority-sort key (8d) ──
+        print("\n[priority: Contacts Priority sort driven by the investor's priority flag]")
+        check((jane or {}).get("priority") is True,
+              f"Jane.priority is True (Acme flagged) (got {(jane or {}).get('priority')!r})")
+        check((pat or {}).get("priority") is False,
+              f"Pat.priority is False (Beta not flagged) (got {(pat or {}).get('priority')!r})")
+        check((vince or {}).get("priority") is False,
+              f"Vince.priority is False (no grid link) (got {(vince or {}).get('priority')!r})")
+
         # ── the get-by-id endpoint carries the same signals (mobile detail sheet, 8b) ──
         print("\n[get-by-id: /api/contacts/{id} also injects committed + pipeline_stage]")
         st, d = _req(port, "GET", f"/api/contacts/{jane['id']}", token)
         detail = (d or {}).get("data") or {}
-        check(st == 200 and detail.get("committed") == 250000 and detail.get("pipeline_stage") == "engaged",
-              f"detail carries committed/pipeline_stage (got committed={detail.get('committed')}, stage={detail.get('pipeline_stage')!r})")
+        check(st == 200 and detail.get("committed") == 250000 and detail.get("pipeline_stage") == "engaged"
+              and detail.get("priority") is True,
+              f"detail carries committed/pipeline_stage/priority (got committed={detail.get('committed')}, stage={detail.get('pipeline_stage')!r}, priority={detail.get('priority')!r})")
         st, d = _req(port, "GET", f"/api/contacts/{vince['id']}", token)
         vdetail = (d or {}).get("data") or {}
-        check(st == 200 and vdetail.get("committed") == 0 and vdetail.get("pipeline_stage") is None,
-              f"unlinked contact detail has committed 0 / stage None (got {vdetail.get('committed')}, {vdetail.get('pipeline_stage')!r})")
+        check(st == 200 and vdetail.get("committed") == 0 and vdetail.get("pipeline_stage") is None
+              and vdetail.get("priority") is False,
+              f"unlinked contact detail has committed 0 / stage None / priority False (got {vdetail.get('committed')}, {vdetail.get('pipeline_stage')!r}, {vdetail.get('priority')!r})")
 
         # ── stage tracks the board: advancing the opp re-derives the contact's stage ──
         print("\n[derived-live: advancing the board stage re-derives the contact's pill]")
@@ -178,6 +190,9 @@ def main():
         jd = (d or {}).get("data") or {}
         check(jd.get("committed") == 500000,
               f"multi-linked contact exposes the higher committed (500000 > 250000) (got {jd.get('committed')})")
+        # The winning (higher-committed) link is Mega Fund LP, which is not flagged → priority follows it.
+        check(jd.get("priority") is False,
+              f"multi-linked contact's priority follows the higher-committed investor (Mega, unflagged) (got {jd.get('priority')!r})")
     finally:
         httpd.shutdown()