Grid/contacts unification step 1: real contact_id link + grid as front door (v0.1.0:52)

Structural fix for the duplicate-people class of bug: instead of matching a grid
contact "pill" to a contacts row heuristically by name/email (which drifted and
caused the 1406 double-count), link them by id.

Backend:
- Migration 0004: fundraising_contacts.contact_id (additive, nullable, logical FK
  to contacts(id)) + index. Paired down migration.
- sync_fundraising_relational now stores the id that _upsert_contact_from_fundraising
  already returns, so every grid contact carries its contacts-table id.
- _backfill_grid_contact_ids: one-time, idempotent backfill on startup (re-runs the
  grid sync once if any row lacks contact_id), so existing data links immediately.
- entity_resolution: grid pass prefers the explicit contact_id link (match_kind
  'grid_link') over heuristic email / name+investor, guarded by a PRAGMA check so
  older DBs without the column still work.

Frontend:
- Fundraising grid "+ Row" -> "+ Investor" (clear, single investor entry point).
- Contacts page: the "+ Add Contact" trigger is replaced by a pointer to the grid;
  the page is now a read/search/edit view (ContactDetailPanel still edits all
  fields). New people are added from the grid. No contact data is removed.

Tests: backend/ingest/test_entity_resolution.py extended (explicit-link case, 11/11)
and a new backend/test_grid_contact_link.py integration test (init_db applies 0004,
sync populates contact_id to the right contact, re-sync is idempotent). py_compile +
frontend html.parser clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/test_grid_contact_link.py

@@ -0,0 +1,76 @@
+#!/usr/bin/env python3
+"""Integration test for the grid→contact id-link wiring (migration 0004 + sync).
+
+Imports the real server module against a throwaway DB, runs init_db (which applies
+the 0004 migration adding fundraising_contacts.contact_id), then drives a grid
+sync and asserts the grid contact is linked to the contacts-table row the app
+created for it. Verifies the end-to-end backend wiring the entity resolver relies on.
+
+Run:  cd backend && python3 test_grid_contact_link.py
+"""
+import os
+import sqlite3
+import sys
+import tempfile
+
+_tmp = tempfile.mkdtemp()
+os.environ["CRM_DATA_DIR"] = _tmp
+os.environ["CRM_DB_PATH"] = os.path.join(_tmp, "crm.db")
+sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+
+import server  # noqa: E402
+
+FAILS = []
+
+
+def check(cond, msg):
+    print(("  PASS " if cond else "  FAIL ") + msg)
+    if not cond:
+        FAILS.append(msg)
+
+
+def main():
+    server.init_db()
+    conn = sqlite3.connect(server.DB_PATH)
+    conn.row_factory = sqlite3.Row
+
+    cols = {r[1] for r in conn.execute("PRAGMA table_info(fundraising_contacts)")}
+    check("contact_id" in cols, "migration 0004 added fundraising_contacts.contact_id")
+
+    grid = {
+        "columns": [
+            {"id": "investor_name", "label": "Investor Name", "type": "text"},
+            {"id": "contacts", "label": "Contacts", "type": "contacts"},
+        ],
+        "rows": [
+            {"id": "row-test-1", "investor_name": "Testco Capital",
+             "contacts": [{"name": "Jane Doe", "email": "jane@testco.com", "title": "Partner"}]},
+        ],
+    }
+    server.sync_fundraising_relational(conn, server.sanitize_fundraising_grid(grid), [])
+    conn.commit()
+
+    fc = conn.execute("SELECT full_name, contact_id FROM fundraising_contacts WHERE full_name='Jane Doe'").fetchone()
+    check(bool(fc and fc["contact_id"]), f"grid contact_id populated by sync (got {dict(fc) if fc else None})")
+
+    if fc and fc["contact_id"]:
+        ct = conn.execute("SELECT id, email FROM contacts WHERE id=?", (fc["contact_id"],)).fetchone()
+        check(bool(ct and ct["email"] == "jane@testco.com"),
+              f"link points to the correct contacts row (got {dict(ct) if ct else None})")
+
+    # Re-sync is idempotent: still exactly one linked contact for Jane.
+    server.sync_fundraising_relational(conn, server.sanitize_fundraising_grid(grid), [])
+    conn.commit()
+    n = conn.execute("SELECT COUNT(*) FROM contacts WHERE lower(email)='jane@testco.com'").fetchone()[0]
+    check(n == 1, f"re-sync does not duplicate the contact (got {n})")
+
+    conn.close()
+    print()
+    if FAILS:
+        print(f"FAILED ({len(FAILS)})")
+        sys.exit(1)
+    print("ALL PASS (grid contact_id link wiring)")
+
+
+if __name__ == "__main__":
+    main()