refactor: trim configuration and drop unused plugins

- Merge sunbather dark/light into one background-aware color scheme
- Fold uninstall.sh into install.sh as a subcommand; drop clone logic
- Inline bash_tools/ helpers; remove fct and odict
- Remove TPM, tmux-sensible, and tmux-fuzzback; tmux has no plugins now
- Remove vim-repeat, vim-fugitive, vim-gitgutter, vim-tmux-navigator,
  and moonfly; everforest is the default dark theme
- Fetch vim-plug via git instead of curl; require git, not curl
- Guard termguicolors on Windows consoles without VT support and set
  nomore before the vimrc loads so headless installs cannot hang
- Fall back to sunbather when a color scheme fails to load, without
  overwriting the saved preference
- Append config/vim to runtimepath so netrw stops writing into the repo
- Fix .editorconfig Python indent; trim .gitignore; update CI and README

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NBfsAH6iJg9inkNLKq11YC

.github/workflows/check.yml

@@ -18,8 +18,8 @@ jobs:
 
       - name: Check shell scripts
         run: |
-          bash -n install.sh uninstall.sh bash_tools.sh bash_tools/*.sh
-          shellcheck install.sh uninstall.sh bash_tools.sh bash_tools/*.sh
+          bash -n install.sh bash_tools.sh
+          shellcheck install.sh bash_tools.sh
 
       - name: Check Python
         run: python3 -m compileall -q win-install.py