Mobile Phase 3a: read + write-supported Fundraising Grid surface

Adds the mobile-first Fundraising Grid (<768px): a lean MobileFundraisingGrid
that reads /api/fundraising/state once and renders an investor card list over
the active view (name, committed $, pipeline-stage chip, staleness-colored
recency, Existing-Investor accent, Priority corner; graveyard muted) with a
bottom-sheet view picker and search. Tap a card -> full-screen detail with
read-only commitments/contacts/notes plus edit sheets: log a note, pipeline
stage, set a reminder, and a "+ New" investor create flow with client-side
dedup typeahead.

All writes go through the targeted one-row endpoints (log-communication,
pipeline link, opportunities stage PATCH, reminders) — NEVER the whole-grid
PUT, which would race the multi-user grid (BRIEF §3a). FundraisingGridPage is
now a useIsMobile() wrapper over the renamed-but-untouched desktop grid and
the new mobile one (rules-of-hooks-safe; desktop unchanged).

Backend: inject a read-only opportunity_id into grid rows
(opportunity_id_by_source_row; added to both strip points) so the mobile detail
can PATCH a linked opp's stage directly. Earliest-opp-wins ordering keeps it
consistent with pipeline_stage and the link's canonical pick.

Editing an existing investor's name + contact pills stays read-only here
(deferred to P3b — needs a narrow per-row PATCH + pill editor).

Tests: test_grid_pipeline_link extended (opportunity_id inject/strip/round-trip);
36/36 backend green, render-smoke green.

backend/test_grid_pipeline_link.py

@@ -167,13 +167,19 @@ def main():
               and rows.get("rowAcme", {}).get("pipeline_stage") == "diligence",
               f"rowAcme pipeline true @diligence (got {rows.get('rowAcme', {}).get('pipeline')}, "
               f"{rows.get('rowAcme', {}).get('pipeline_stage')})")
+        # Read-only opportunity_id is injected for a linked row so the mobile grid detail can
+        # PATCH the stage on the opportunities endpoint (the grid row carries no opp id otherwise).
+        check(rows.get("rowAcme", {}).get("opportunity_id") == opp_id,
+              f"rowAcme carries the live opportunity_id (got {rows.get('rowAcme', {}).get('opportunity_id')}, want {opp_id})")
         # Phase 0 derived signals are injected read-only on every row (values depend on seed;
         # assert the keys are present so the strip/inject round-trip below is meaningful).
         check(all(k in rows.get("rowAcme", {}) for k in ("existing_investor", "staleness", "last_activity_at")),
               f"rowAcme carries derived existing_investor/staleness/last_activity (keys: {sorted(rows.get('rowAcme', {}).keys())})")
         check(rows.get("rowBeta", {}).get("pipeline") is False
-              and rows.get("rowBeta", {}).get("pipeline_stage") == "",
-              f"rowBeta not in pipeline (got {rows.get('rowBeta', {}).get('pipeline')})")
+              and rows.get("rowBeta", {}).get("pipeline_stage") == ""
+              and rows.get("rowBeta", {}).get("opportunity_id") == "",
+              f"rowBeta not in pipeline (got {rows.get('rowBeta', {}).get('pipeline')}, "
+              f"opp_id={rows.get('rowBeta', {}).get('opportunity_id')!r})")
 
         # ── round-trip: a save echoing the injected read-only values is lossless ──
         print("\n[round-trip: PUT carrying injected pipeline values strips them, link intact]")
@@ -186,13 +192,14 @@ def main():
         blob = json.loads(c.execute("SELECT grid_json FROM fundraising_state WHERE id='main'").fetchone()[0])
         c.close()
         stored_acme = {r["id"]: r for r in blob.get("rows", [])}.get("rowAcme", {})
-        check(not any(k in stored_acme for k in ("pipeline", "pipeline_stage", "existing_investor",
-                                                  "staleness", "last_activity_at")),
-              "computed keys (pipeline + existing_investor/staleness/last_activity) NOT persisted into the grid blob")
+        check(not any(k in stored_acme for k in ("pipeline", "pipeline_stage", "opportunity_id",
+                                                  "existing_investor", "staleness", "last_activity_at")),
+              "computed keys (pipeline + opportunity_id + existing_investor/staleness/last_activity) NOT persisted into the grid blob")
         st, d = _req(port, "GET", "/api/fundraising/state", token)
         rt = {r["id"]: r for r in (d or {}).get("data", {}).get("grid", {}).get("rows", [])}.get("rowAcme", {})
-        check(rt.get("pipeline") is True and rt.get("pipeline_stage") == "diligence",
-              f"pipeline values re-injected after round-trip (got {rt.get('pipeline')}, {rt.get('pipeline_stage')})")
+        check(rt.get("pipeline") is True and rt.get("pipeline_stage") == "diligence"
+              and rt.get("opportunity_id") == opp_id,
+              f"pipeline values re-injected after round-trip (got {rt.get('pipeline')}, {rt.get('pipeline_stage')}, opp_id={rt.get('opportunity_id')!r})")
         check(all(k in rt for k in ("existing_investor", "staleness", "last_activity_at")),
               "derived signals re-injected after round-trip")