Initial bridge: Discord <-> Fluxer channel relay via webhooks

- discord.py + fluxer.py bots run side-by-side in one asyncio process
- messages relay through per-channel incoming webhooks with the original
  author's name and avatar (suffixed '(Discord)' / '(Fluxer)')
- loop protection: bot-authored and webhook-authored messages are ignored
- attachments re-uploaded natively both directions (8 MB cap)
- emoji mirroring: on-demand upload into the receiving guild with LRU
  eviction of bridge-created emojis only; pre-existing emojis untouched;
  to-Discord direction opt-in (50-slot default guild cap)

.gitignore

@@ -131,7 +131,7 @@ venv.bak/
 
 # Spyder project settings
 .spyderproject
-.spyproject
+.spyderproject
 
 # Rope project settings
 .ropeproject
@@ -160,3 +160,5 @@ cython_debug/
 #  option (not recommended) you can uncomment the following to ignore the entire idea folder.
 #.idea/
 
+# itako
+dbg/