feat: add groups to search vector

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/database-schema-readme.md

@@ -233,16 +233,23 @@ Settings (1) → MembershipFeeType (0..1)
 ## Full-Text Search
 
 ### Implementation
-- **Trigger:** `members_search_vector_trigger()`
-- **Function:** Automatically updates `search_vector` on INSERT/UPDATE
+- **Trigger:** `members_search_vector_trigger()` on `members` (INSERT/UPDATE)
+- **Trigger:** `update_member_search_vector_from_member_groups()` on `member_groups` (INSERT/UPDATE/DELETE)
+- **Function:** Automatically updates `search_vector` on member and member_groups changes
 - **Index Type:** GIN (Generalized Inverted Index)
 
 ### Weighted Fields
 - **Weight A (highest):** first_name, last_name
-- **Weight B:** email, notes
+- **Weight B:** email, notes, group names (from member_groups → groups)
 - **Weight C:** city, street, house_number, postal_code, custom_field_values
 - **Weight D (lowest):** join_date, exit_date
 
+### Group Names in Search
+Group names are included in the member search vector so that searching for a group name (e.g. "Vorstand") finds all members in that group:
+- Group names are aggregated from `member_groups` joined with `groups` and receive weight 'B'
+- The trigger `update_member_search_vector_on_member_groups_change` runs on INSERT/UPDATE/DELETE on `member_groups` and refreshes the affected member's `search_vector`
+- See migration `20260217120000_add_group_names_to_member_search_vector.exs` (Issue #375)
+
 ### Custom Field Values in Search
 Custom field values are automatically included in the search vector:
 - All custom field values (string, integer, boolean, date, email) are aggregated and added to the search vector