Remove packer-era and dead config files

.luarc.json referenced ~90 packer plugins under a /home/thallada path and a
linuxbrew nvim that no longer exists; lazydev.nvim covers this now. .stylua.toml
was shadowed by stylua.toml and its settings never applied. .gitignore only held
packer_compiled.lua, and disabled.lua returned an empty table.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

lua/plugins/disabled.lua

@@ -1 +0,0 @@
-return {}