Add app_legal_channel to helpers package (fixes import error)

Bug: Version 1.7.5 added app_legal_channel to helpers.py but production uses
the helpers/ package which imports from helpers/main.py. This caused:
- NameError: name 'app_legal_channel' is not defined
- ImportError: cannot import name 'app_legal_channel' from 'helpers'

Result: cogs.economy and cogs.players failed to load, causing all slash
commands (including /team, /selldupes, /comeonmanineedthis) to be unavailable.

Fix: Add app_legal_channel() function to helpers/main.py so it's exported
via the helpers package __init__.py.

Bumps version to 1.7.6

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

VERSION

@@ -1 +1 @@
-1.7.5
+1.7.6

helpers/main.py

@@ -1022,6 +1022,18 @@ async def legal_channel(ctx):
         return True
 
 
+def app_legal_channel():
+    """Check for slash commands (app_commands). Use as @app_legal_channel()"""
+    async def predicate(interaction: discord.Interaction) -> bool:
+        bad_channels = ['paper-dynasty-chat', 'pd-news-ticker', 'pd-network-news']
+        if interaction.channel.name in bad_channels:
+            raise discord.app_commands.CheckFailure(
+                f'Slide on down to the {get_channel(interaction, "pd-bot-hole").mention} ;)'
+            )
+        return True
+    return discord.app_commands.check(predicate)
+
+
 def is_ephemeral_channel(channel) -> bool:
     """Check if channel requires ephemeral responses (chat channels)."""
     if not channel or not hasattr(channel, 'name'):