docs: add @doc to public functions in EmailSync, Validations, and Senders

Document public API functions with @doc for better tooling support:
- EmailSync Changes: sync_user_email_to_member, sync_member_email_to_user
- Validations: email_not_used_by_other_member, email_not_used_by_other_user
- Senders: send_new_user_confirmation_email, send_password_reset_email

lib/mv/accounts/user/senders/send_new_user_confirmation_email.ex

@@ -10,6 +10,20 @@ defmodule Mv.Accounts.User.Senders.SendNewUserConfirmationEmail do
 
   alias Mv.Mailer
 
+  @doc """
+  Sends a confirmation email to a new user.
+
+  This function is called automatically by AshAuthentication when a new
+  user registers and needs to confirm their email address.
+
+  ## Parameters
+  - `user` - The user record who needs to confirm their email
+  - `token` - The confirmation token to include in the email link
+  - `_opts` - Additional options (unused)
+
+  ## Returns
+  The Swoosh.Email delivery result from `Mailer.deliver!/1`.
+  """
   @impl true
   def send(user, token, _) do
     new()

lib/mv/accounts/user/senders/send_password_reset_email.ex

@@ -10,6 +10,20 @@ defmodule Mv.Accounts.User.Senders.SendPasswordResetEmail do
 
   alias Mv.Mailer
 
+  @doc """
+  Sends a password reset email to a user.
+
+  This function is called automatically by AshAuthentication when a user
+  requests a password reset.
+
+  ## Parameters
+  - `user` - The user record requesting the password reset
+  - `token` - The password reset token to include in the email link
+  - `_opts` - Additional options (unused)
+
+  ## Returns
+  The Swoosh.Email delivery result from `Mailer.deliver!/1`.
+  """
   @impl true
   def send(user, token, _) do
     new()

lib/mv/accounts/user/validations/email_not_used_by_other_member.ex

@@ -9,6 +9,22 @@ defmodule Mv.Accounts.User.Validations.EmailNotUsedByOtherMember do
   """
   use Ash.Resource.Validation
 
+  @doc """
+  Validates email uniqueness across linked User-Member pairs.
+
+  This validation ensures that when a user is linked to a member, their email
+  does not conflict with another member's email. It only runs when necessary
+  to avoid blocking valid operations (see `@moduledoc` for trigger conditions).
+
+  ## Parameters
+  - `changeset` - The Ash changeset being validated
+  - `_opts` - Options passed to the validation (unused)
+  - `_context` - Ash context map (unused)
+
+  ## Returns
+  - `:ok` if validation passes or should be skipped
+  - `{:error, field: :email, message: ..., value: ...}` if validation fails
+  """
   @impl true
   def validate(changeset, _opts, _context) do
     email_changing? = Ash.Changeset.changing_attribute?(changeset, :email)

lib/mv/email_sync/changes/sync_member_email_to_user.ex

@@ -10,6 +10,21 @@ defmodule Mv.EmailSync.Changes.SyncMemberEmailToUser do
   use Ash.Resource.Change
   alias Mv.EmailSync.{Helpers, Loader}
 
+  @doc """
+  Implements the email synchronization from Member to User.
+
+  This function is called automatically by Ash when the configured trigger
+  conditions are met (see `@moduledoc` for trigger details).
+
+  ## Parameters
+  - `changeset` - The Ash changeset being processed
+  - `_opts` - Options passed to the change (unused)
+  - `context` - Ash context map containing metadata (e.g., `:syncing_email` flag)
+
+  ## Returns
+  Modified changeset with email synchronization applied, or original changeset
+  if recursion detected.
+  """
   @impl true
   def change(changeset, _opts, context) do
     # Only recursion protection needed - trigger logic is in `where` clauses

lib/mv/email_sync/changes/sync_user_email_to_member.ex

@@ -12,6 +12,21 @@ defmodule Mv.EmailSync.Changes.SyncUserEmailToMember do
   use Ash.Resource.Change
   alias Mv.EmailSync.{Helpers, Loader}
 
+  @doc """
+  Implements the email synchronization from User to Member.
+
+  This function is called automatically by Ash when the configured trigger
+  conditions are met (see `@moduledoc` for trigger details).
+
+  ## Parameters
+  - `changeset` - The Ash changeset being processed
+  - `_opts` - Options passed to the change (unused)
+  - `context` - Ash context map containing metadata (e.g., `:syncing_email` flag)
+
+  ## Returns
+  Modified changeset with email synchronization applied, or original changeset
+  if recursion detected.
+  """
   @impl true
   def change(changeset, _opts, context) do
     # Only recursion protection needed - trigger logic is in `where` clauses

lib/mv/membership/member/validations/email_not_used_by_other_user.ex

@@ -9,6 +9,22 @@ defmodule Mv.Membership.Member.Validations.EmailNotUsedByOtherUser do
   """
   use Ash.Resource.Validation
 
+  @doc """
+  Validates email uniqueness across linked Member-User pairs.
+
+  This validation ensures that when a member is linked to a user, their email
+  does not conflict with another user's email. It only runs when necessary
+  to avoid blocking valid operations (see `@moduledoc` for trigger conditions).
+
+  ## Parameters
+  - `changeset` - The Ash changeset being validated
+  - `_opts` - Options passed to the validation (unused)
+  - `_context` - Ash context map (unused)
+
+  ## Returns
+  - `:ok` if validation passes or should be skipped
+  - `{:error, field: :email, message: ..., value: ...}` if validation fails
+  """
   @impl true
   def validate(changeset, _opts, _context) do
     email_changing? = Ash.Changeset.changing_attribute?(changeset, :email)