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/ingest/entity_resolution.py

@@ -220,27 +220,29 @@ def resolve_people(conn, org_canon_by_orgid, org_canon_by_fundinv, merge_map=Non
         if cid:
             contact_to_person[r["id"]] = cid
 
-    # 2. Grid contacts are associations, not new people: match to a contact-person
-    #    (by email, else name within the same investor) and just add membership.
-    #    Only create a person when there is genuinely no matching contact.
-    for r in conn.execute("SELECT id, full_name, email, investor_id FROM fundraising_contacts"):
+    # 2. Grid contacts are associations, not new people: link each to its
+    #    contacts-table person and record membership. We prefer the EXPLICIT
+    #    contact_id link (migration 0004 — the grid pill stores the id of the
+    #    contact it was created from), and fall back to provable email / exact name
+    #    within the same investor for rows not yet backfilled. On a miss we
+    #    deliberately do NOT mint a person: the old else-branch mint is exactly what
+    #    produced the people double-count, and guessing by name across firms risks
+    #    binding two different same-named people — honest separation, never on a guess.
+    fc_cols = {row[1] for row in conn.execute("PRAGMA table_info(fundraising_contacts)")}
+    has_contact_id = "contact_id" in fc_cols
+    sel = ("SELECT id, full_name, email, investor_id" +
+           (", contact_id" if has_contact_id else "") + " FROM fundraising_contacts")
+    for r in conn.execute(sel):
         email = norm_email(r["email"])
         name_norm = norm_text(r["full_name"] or "")
         inv_canon = org_canon_by_fundinv.get(r["investor_id"])
-        # Match the grid contact to its contacts-table person by PROVABLE keys only:
-        # exact email, else exact name within the SAME canonical investor. The app
-        # keeps the grid and the contacts table in sync (_upsert_contact_from_
-        # fundraising), so a grid contact IS an existing contact-person, never a new
-        # one. On a confident match, record the membership. On a miss we deliberately
-        # do NOT mint a person: the old else-branch mint is exactly what produced the
-        # people double-count (a grid row whose (name, investor) key didn't line up
-        # with its contact minted a duplicate), and guessing by name across firms
-        # risks binding two different same-named people. Unresolved grid rows are
-        # left for the explicit contact_id link planned in the grid/contacts
-        # unification — honest separation: never merge or mint on a guess.
-        cid = (by_email.get(email) if email else None) or by_name_inv.get((name_norm, inv_canon or ""))
+        link_cid = r["contact_id"] if has_contact_id else None
+        cid = (contact_to_person.get(link_cid) if link_cid else None) \
+            or (by_email.get(email) if email else None) \
+            or by_name_inv.get((name_norm, inv_canon or ""))
         if cid:
-            _link(conn, cid, "fundraising_contacts", r["id"], email or name_norm, "grid_assoc", 0.9)
+            mk = "grid_link" if (link_cid and contact_to_person.get(link_cid)) else "grid_assoc"
+            _link(conn, cid, "fundraising_contacts", r["id"], email or name_norm, mk, 0.95 if mk == "grid_link" else 0.9)
             _member_of(conn, cid, inv_canon)
 
     # lp_profiles -> the person entity of its contact