Remove stale documentation of removed join_date future-date restriction

docs/database-schema-readme.md

@@ -188,7 +188,6 @@ Settings (1) → MembershipFeeType (0..1)
 ### Member Constraints
 - First name and last name required (min 1 char)
 - Email unique, validated format (5-254 chars)
-- Join date cannot be in future
 - Exit date must be after join date
 - Phone: `+?[0-9\- ]{6,20}`
 - Postal code: optional (no format validation)

docs/database_schema.dbml

@@ -124,7 +124,7 @@ Table members {
   first_name text [null, note: 'Member first name (min length: 1 if present)']
   last_name text [null, note: 'Member last name (min length: 1 if present)']
   email text [not null, unique, note: 'Member email address (5-254 chars, validated)']
-  join_date date [null, note: 'Date when member joined club (cannot be in future)']
+  join_date date [null, note: 'Date when member joined club']
   exit_date date [null, note: 'Date when member left club (must be after join_date)']
   notes text [null, note: 'Additional notes about member']
   city text [null, note: 'City of residence']
@@ -187,7 +187,6 @@ Table members {
     **Validation Rules:**
     - first_name, last_name: optional, but if present min 1 character
     - email: 5-254 characters, valid email format (required)
-    - join_date: cannot be in future
     - exit_date: must be after join_date (if both present)
     - postal_code: optional (no format validation)
     - country: optional

lib/membership/member.ex

@@ -22,7 +22,7 @@ defmodule Mv.Membership.Member do
   ## Validations
   - Required: email (all other fields are optional)
   - Email format validation (using EctoCommons.EmailValidator)
-  - Date validations: join_date not in future, exit_date after join_date
+  - Date validations: exit_date after join_date
   - Email uniqueness: prevents conflicts with unlinked users
   - Linked member email change: only admins or the linked user may change a linked member's email (see `Mv.Membership.Member.Validations.EmailChangePermission`)