docs: update the docs

docs/database_schema.dbml

@@ -6,8 +6,8 @@
 // - https://dbdocs.io
 // - VS Code Extensions: "DBML Language" or "dbdiagram.io"
 //
-// Version: 1.0
-// Last Updated: 2025-11-10
+// Version: 1.1
+// Last Updated: 2025-11-13
 
 Project mila_membership_management {
   database_type: 'PostgreSQL'
@@ -17,15 +17,21 @@ Project mila_membership_management {
     A membership management application for small to mid-sized clubs.
     
     ## Key Features:
-    - User authentication (OIDC + Password)
+    - User authentication (OIDC + Password with secure account linking)
     - Member management with flexible custom properties
     - Bidirectional email synchronization between users and members
-    - Full-text search capabilities
+    - Full-text search capabilities (tsvector)
+    - Fuzzy search with trigram matching (pg_trgm)
     - GDPR-compliant data management
     
     ## Domains:
     - **Accounts**: User authentication and session management
     - **Membership**: Club member data and custom properties
+    
+    ## Required PostgreSQL Extensions:
+    - uuid-ossp (UUID generation)
+    - citext (case-insensitive text)
+    - pg_trgm (trigram-based fuzzy search)
   '''
 }
 
@@ -130,10 +136,16 @@ Table members {
   
   indexes {
     email [unique, name: 'members_unique_email_index']
-    search_vector [type: gin, name: 'members_search_vector_idx', note: 'GIN index for full-text search']
-    email [name: 'members_email_idx']
-    last_name [name: 'members_last_name_idx', note: 'For name sorting']
-    join_date [name: 'members_join_date_idx', note: 'For date filters']
+    search_vector [type: gin, name: 'members_search_vector_idx', note: 'GIN index for full-text search (tsvector)']
+    first_name [type: gin, name: 'members_first_name_trgm_idx', note: 'GIN trigram index for fuzzy search']
+    last_name [type: gin, name: 'members_last_name_trgm_idx', note: 'GIN trigram index for fuzzy search']
+    email [type: gin, name: 'members_email_trgm_idx', note: 'GIN trigram index for fuzzy search']
+    city [type: gin, name: 'members_city_trgm_idx', note: 'GIN trigram index for fuzzy search']
+    street [type: gin, name: 'members_street_trgm_idx', note: 'GIN trigram index for fuzzy search']
+    notes [type: gin, name: 'members_notes_trgm_idx', note: 'GIN trigram index for fuzzy search']
+    email [name: 'members_email_idx', note: 'B-tree index for exact lookups']
+    last_name [name: 'members_last_name_idx', note: 'B-tree index for name sorting']
+    join_date [name: 'members_join_date_idx', note: 'B-tree index for date filters']
     (paid) [name: 'members_paid_idx', type: btree, note: 'Partial index WHERE paid IS NOT NULL']
   }
   
@@ -152,10 +164,17 @@ Table members {
     - Subsequent changes to either email sync bidirectionally
     - Validates that email is not already used by another unlinked user
     
-    **Full-Text Search:**
-    - `search_vector` is auto-updated via trigger
-    - Weighted fields: first_name (A), last_name (A), email (B), notes (B)
-    - Supports flexible member search across multiple fields
+    **Search Capabilities:**
+    1. Full-Text Search (tsvector):
+       - `search_vector` is auto-updated via trigger
+       - Weighted fields: first_name (A), last_name (A), email (B), notes (B)
+       - GIN index for fast text search
+    
+    2. Fuzzy Search (pg_trgm):
+       - Trigram-based similarity matching
+       - 6 GIN trigram indexes on searchable fields
+       - Configurable similarity threshold (default 0.2)
+       - Supports typos and partial matches
     
     **Relationships:**
     - Optional 1:1 with users (0..1 ↔ 0..1) - authentication account