feat: add start_link/1 and child_spec/1 delegations to Phoenix.SessionProcess

Add start_link/1 and child_spec/1 functions that delegate to
Phoenix.SessionProcess.Supervisor, allowing users to use the cleaner
syntax {Phoenix.SessionProcess, []} in their supervision tree instead
of {Phoenix.SessionProcess.Supervisor, []}.

Changes:
- Added defdelegate start_link/1 to Phoenix.SessionProcess.Supervisor
- Added defdelegate child_spec/1 to Phoenix.SessionProcess.Supervisor
- Updated documentation in Phoenix.SessionProcess module docstring
- Updated README.md Quick Start example
- Updated CLAUDE.md configuration example

This provides a cleaner, more intuitive API for users while maintaining
backward compatibility with the explicit Supervisor module usage.

Example:
  # New cleaner syntax
  {Phoenix.SessionProcess, []}

  # Still works
  {Phoenix.SessionProcess.Supervisor, []}

Author: GSMLG-BOT

CLAUDE.md

@@ -411,7 +411,8 @@ config :phoenix_session_process,
 # lib/my_app/application.ex
 def start(_type, _args) do
   children = [
-    Phoenix.SessionProcess.Supervisor,
+    {Phoenix.SessionProcess, []},
+    # Or: Phoenix.SessionProcess.Supervisor,
     # ... other children
   ]
 

README.md

@@ -59,7 +59,8 @@ Add the supervisor to your application's supervision tree:
 def start(_type, _args) do
   children = [
     # ... other children ...
-    {Phoenix.SessionProcess.Supervisor, []}
+    {Phoenix.SessionProcess, []}
+    # Or use: {Phoenix.SessionProcess.Supervisor, []}
   ]
 
   Supervisor.start_link(children, strategy: :one_for_one)

lib/phoenix/session_process.ex

@@ -24,7 +24,8 @@ defmodule Phoenix.SessionProcess do
       def start(_type, _args) do
         children = [
           # ... other children ...
-          {Phoenix.SessionProcess.Supervisor, []}
+          {Phoenix.SessionProcess, []}
+          # Or use: {Phoenix.SessionProcess.Supervisor, []}
         ]
 
         Supervisor.start_link(children, strategy: :one_for_one)
@@ -151,6 +152,61 @@ defmodule Phoenix.SessionProcess do
   alias Phoenix.SessionProcess.{Cleanup, Config, ProcessSupervisor}
   alias Phoenix.SessionProcess.Registry, as: SessionRegistry
 
+  @doc """
+  Starts the SessionProcess supervision tree.
+
+  This function delegates to `Phoenix.SessionProcess.Supervisor.start_link/1` and
+  should be used in your application's supervision tree for cleaner syntax.
+
+  ## Parameters
+  - `init_arg` - Initialization argument (typically an empty list `[]`)
+
+  ## Returns
+  - `{:ok, pid}` - Supervisor started successfully
+  - `{:error, reason}` - If supervisor failed to start
+
+  ## Examples
+
+  In your application supervision tree:
+
+      def start(_type, _args) do
+        children = [
+          # Cleaner syntax using Phoenix.SessionProcess
+          {Phoenix.SessionProcess, []}
+
+          # Or explicitly use the Supervisor module
+          {Phoenix.SessionProcess.Supervisor, []}
+        ]
+
+        Supervisor.start_link(children, strategy: :one_for_one)
+      end
+  """
+  @spec start_link(any()) :: Supervisor.on_start()
+  defdelegate start_link(init_arg), to: Phoenix.SessionProcess.Supervisor
+
+  @doc """
+  Returns a child specification for starting the SessionProcess supervision tree.
+
+  This is automatically called when adding `{Phoenix.SessionProcess, []}` to a
+  supervision tree. The function delegates to `Phoenix.SessionProcess.Supervisor.child_spec/1`.
+
+  ## Parameters
+  - `init_arg` - Initialization argument passed to `start_link/1`
+
+  ## Returns
+  - Child specification map with `:id`, `:start`, and other supervisor options
+
+  ## Examples
+
+  The child spec is automatically used in supervision trees:
+
+      children = [
+        {Phoenix.SessionProcess, []}  # child_spec/1 is called automatically
+      ]
+  """
+  @spec child_spec(any()) :: Supervisor.child_spec()
+  defdelegate child_spec(init_arg), to: Phoenix.SessionProcess.Supervisor
+
   @doc """
   Starts a session process using the default configured module.