Integrate Copilot with Blink.cmp

- Switch from copilot.vim to zbirenbaum/copilot.lua
- Add blink-cmp-copilot for completion integration
- Configure Blink to show Copilot in completion menu
- Fix plugin import issues

Testing in progress - can be reverted if needed

.envrc

@@ -1,11 +1 @@
 export PROJECT=$(basename $(pwd))
-
-# Get the git project root
-export PROJECT_ROOT=$(git rev-parse --show-toplevel 2>/dev/null || pwd)
-
-# Set Lua paths for Neovim to find our modules
-export LUA_PATH="$PROJECT_ROOT/lua/?.lua;$PROJECT_ROOT/lua/?/init.lua;;"
-export LUA_CPATH="$PROJECT_ROOT/lua/?.so;;"
-
-# Optional: Set NVIM_APPNAME for isolated testing
-export NVIM_APPNAME="nvim-$PROJECT"