feat: cross-chat search deep-links to turn via memories.event_id (T111.2)

Add ``m.event_id`` (T109's nullable column from migration 0014) to
``search_all_memories``'s SELECT, propagate it through the route's
template context, and have ``search.html`` build result links as
``/chats/{chat_id}#turn-{event_id}`` — matching the ``id="turn-{event_id}"``
anchor that Phase 3.5 T86 stamps on each turn DOM node so the chat page
scrolls to the originating turn on load. Memory rows projected before
the 0014 migration ran read NULL ``event_id``; the template falls back
to a chat-level link in that case so we never emit ``#turn-None``.

Pre-existing tests that asserted on the bare ``href="/chats/{chat_id}"``
contract are updated to assert on the ``href="/chats/{chat_id}#turn-``
prefix to reflect the new deep-link.

tests/test_phase4_integration.py

@@ -867,12 +867,14 @@ def test_cross_chat_search_surfaces_memories_in_three_chats(
     assert response.status_code == 200
     body = response.text
 
-    # Each chat_id appears in a result link href, e.g.
-    # ``href="/chats/chat_bot_a"``. The template renders one
-    # ``<a class="search-result-link" href="/chats/{chat_id}">`` per
-    # row, so a substring match per chat is sufficient.
+    # Each chat_id appears in a result link href. T111.2 deep-links to
+    # the originating turn so the href is now
+    # ``href="/chats/{chat_id}#turn-{event_id}"``; we assert on the
+    # ``"/chats/{chat_id}#turn-`` prefix so the per-chat link is
+    # uniquely matched (a bare ``"/chats/chat_bot_a`` substring would
+    # also match ``chat_bot_a_2`` / ``chat_bot_a_3``).
     for chat_id in chat_ids:
-        assert f'href="/chats/{chat_id}"' in body, (
+        assert f'href="/chats/{chat_id}#turn-' in body, (
             f"chat {chat_id} missing from /search results: {body!r}"
         )
     # The owner display name (BotA) renders for each row — verify >= 3
@@ -888,4 +890,4 @@ def test_cross_chat_search_surfaces_memories_in_three_chats(
     # The "no matches" empty-state copy fires.
     assert "No matches" in distractor_body
     for chat_id in chat_ids:
-        assert f'href="/chats/{chat_id}"' not in distractor_body
+        assert f'href="/chats/{chat_id}#turn-' not in distractor_body

tests/test_search_ux.py

@@ -127,13 +127,19 @@ def test_empty_query_renders_placeholder_not_results(client, tmp_path):
 
 def test_result_links_navigate_to_chat(client, tmp_path):
     """Each result links back to its originating chat so the user can
-    reopen the thread where the memory was first witnessed."""
+    reopen the thread where the memory was first witnessed.
+
+    Post-T111.2: the link now includes a turn anchor when the memory
+    row carries an ``event_id`` (T109's nullable column is populated for
+    rows projected after migration 0014 ran). We assert on the chat-id
+    portion of the href because the exact event id is autoincrement and
+    depends on seed order; the dedicated
+    ``test_search_result_link_includes_turn_anchor`` test below pins the
+    anchor format itself."""
     _seed_two_chats_with_memories(tmp_path / "test.db")
     resp = client.get("/search?q=rabbit")
     assert resp.status_code == 200
-    # The link target is chat-level (memories don't carry an event_id
-    # column today, so we don't deep-link to a specific turn).
-    assert 'href="/chats/chat_a"' in resp.text
+    assert 'href="/chats/chat_a' in resp.text
 
 
 def test_search_results_include_fts_snippet_with_highlight(client, tmp_path):
@@ -152,6 +158,22 @@ def test_search_results_include_fts_snippet_with_highlight(client, tmp_path):
     assert "<mark>rabbit</mark>" in resp.text
 
 
+def test_search_result_link_includes_turn_anchor(client, tmp_path):
+    """T111.2: result links deep-link to the originating turn via the
+    chat-page anchor stamped by Phase 3.5 T86 (``id="turn-{event_id}"``).
+
+    The seeded ``memory_written`` events are projected with
+    ``memories.event_id`` populated (T109); the route exposes that id and
+    the template builds the link as ``/chats/{chat_id}#turn-{event_id}``.
+    We don't assert a specific event id (it's an autoincrement that
+    depends on seed order), only that *some* turn anchor is present for
+    the chat link the user is about to click."""
+    _seed_two_chats_with_memories(tmp_path / "test.db")
+    resp = client.get("/search?q=rabbit")
+    assert resp.status_code == 200
+    assert "/chats/chat_a#turn-" in resp.text
+
+
 def test_search_results_use_batched_lookups(client, tmp_path):
     """T106: hydration must not fan out to per-row ``get_bot``/
     ``get_chat``/``get_scene`` calls.