chore: update docs

docs/database-schema-readme.md

@@ -15,10 +15,10 @@ This document provides a comprehensive overview of the Mila Membership Managemen
 
 | Metric | Count |
 |--------|-------|
-| **Tables** | 5 |
-| **Domains** | 2 (Accounts, Membership) |
-| **Relationships** | 3 |
-| **Indexes** | 15+ |
+| **Tables** | 9 |
+| **Domains** | 4 (Accounts, Membership, MembershipFees, Authorization) |
+| **Relationships** | 7 |
+| **Indexes** | 20+ |
 | **Triggers** | 1 (Full-text search) |
 
 ## Tables Overview
@@ -68,16 +68,39 @@ This document provides a comprehensive overview of the Mila Membership Managemen
   - Immutable and required flags
   - Centralized custom field management
 
+#### `settings`
+- **Purpose:** Global application settings (singleton resource)
+- **Rows (Estimated):** 1 (singleton pattern)
+- **Key Features:**
+  - Club name configuration
+  - Member field visibility settings
+  - Membership fee default settings
+  - Environment variable support for club name
+
+### Authorization Domain
+
+#### `roles`
+- **Purpose:** Role-based access control (RBAC)
+- **Rows (Estimated):** Low (typically 3-10 roles)
+- **Key Features:**
+  - Links users to permission sets
+  - System role protection
+  - Four hardcoded permission sets: own_data, read_only, normal_user, admin
+
 ## Key Relationships
 
 ```
 User (0..1) ←→ (0..1) Member
-       ↓
-    Tokens (N)
+       ↓              ↓
+    Tokens (N)    CustomFieldValues (N)
+       ↓                    ↓
+    Role (N:1)        CustomField (1)
 
-Member (1) → (N) Properties
+Member (1) → (N) MembershipFeeCycles
                     ↓
-              CustomField (1)
+            MembershipFeeType (1)
+
+Settings (1) → MembershipFeeType (0..1)
 ```
 
 ### Relationship Details
@@ -89,16 +112,39 @@ Member (1) → (N) Properties
    - Email synchronization when linked (User.email is source of truth)
    - `ON DELETE SET NULL` on user side (User preserved when Member deleted)
 
-2. **Member → Properties (1:N)**
+2. **User → Role (N:1)**
+   - Many users can be assigned to one role
+   - `ON DELETE RESTRICT` - cannot delete role if users are assigned
+   - Role links user to permission set for authorization
+
+3. **Member → CustomFieldValues (1:N)**
    - One member, many custom_field_values
    - `ON DELETE CASCADE` - custom_field_values deleted with member
    - Composite unique constraint (member_id, custom_field_id)
 
-3. **CustomFieldValue → CustomField (N:1)**
-   - Properties reference type definition
+4. **CustomFieldValue → CustomField (N:1)**
+   - Custom field values reference type definition
    - `ON DELETE RESTRICT` - cannot delete type if in use
    - Type defines data structure
 
+5. **Member → MembershipFeeType (N:1, optional)**
+   - Many members can be assigned to one fee type
+   - `ON DELETE RESTRICT` - cannot delete fee type if members are assigned
+   - Optional relationship (member can have no fee type)
+
+6. **Member → MembershipFeeCycles (1:N)**
+   - One member, many billing cycles
+   - `ON DELETE CASCADE` - cycles deleted when member deleted
+   - Unique constraint (member_id, cycle_start)
+
+7. **MembershipFeeCycle → MembershipFeeType (N:1)**
+   - Many cycles reference one fee type
+   - `ON DELETE RESTRICT` - cannot delete fee type if cycles exist
+
+8. **Settings → MembershipFeeType (N:1, optional)**
+   - Settings can reference a default fee type
+   - `ON DELETE SET NULL` - if fee type is deleted, setting is cleared
+
 ## Important Business Rules
 
 ### Email Synchronization
@@ -464,7 +510,7 @@ mix run priv/repo/seeds.exs
 
 ---
 
-**Last Updated:** 2025-11-13  
-**Schema Version:** 1.1  
+**Last Updated:** 2026-01-13  
+**Schema Version:** 1.4  
 **Database:** PostgreSQL 17.6 (dev) / 16 (prod)