feat: add configurable Ecto query log level

Add centralized log level configuration for Ecto queries following
Oban's wrapper pattern. This eliminates excessive debug-level SQL
query logs by default.

- Add `log_level` config option (default: false, disables query logging)
- Create `Durable.Repo` wrapper module that applies log level to all queries
- Update all direct repo calls to use the wrapper

Usage:
  # Default: query logging disabled
  {Durable, repo: MyApp.Repo}

  # Enable debug logging for troubleshooting
  {Durable, repo: MyApp.Repo, log_level: :debug}

Author: kasvith

lib/durable/config.ex

@@ -14,6 +14,7 @@ defmodule Durable.Config do
   * `:queue_enabled` - Enable/disable queue processing (default: `true`)
   * `:stale_lock_timeout` - Seconds before a lock is considered stale (default: `300`)
   * `:heartbeat_interval` - Milliseconds between worker heartbeats (default: `30_000`)
+  * `:log_level` - Log level for Ecto queries, or `false` to disable (default: `false`)
 
   ## Examples
 
@@ -43,7 +44,8 @@ defmodule Durable.Config do
           stale_lock_timeout: pos_integer(),
           heartbeat_interval: pos_integer(),
           scheduled_modules: [module()],
-          scheduler_interval: pos_integer()
+          scheduler_interval: pos_integer(),
+          log_level: false | :debug | :info | :warning | :error
         }
 
   defstruct [
@@ -55,7 +57,8 @@ defmodule Durable.Config do
     :stale_lock_timeout,
     :heartbeat_interval,
     :scheduled_modules,
-    :scheduler_interval
+    :scheduler_interval,
+    :log_level
   ]
 
   @schema [
@@ -103,6 +106,11 @@ defmodule Durable.Config do
       type: :pos_integer,
       default: 60_000,
       doc: "Milliseconds between scheduler polls for due schedules"
+    ],
+    log_level: [
+      type: {:in, [false, :debug, :info, :warning, :error]},
+      default: false,
+      doc: "Log level for Ecto queries (false disables logging, default: false)"
     ]
   ]