Expand LSP and lint coverage for full-stack languages (fixes #6)

ALE linters:
- Add css/scss: stylelint
- Add markdown: markdownlint
- Add sql: sqlfluff

ALE fixers:
- Add scss, less: prettier
- Add sql: sqlfmt

vim-lsp fallback (no Node.js path):
- Add html, css, scss, json, yaml: vscode language servers
- Add markdown: marksman
- Add sql: sqls

install.sh (CoC path):
- Add coc-go, coc-rust-analyzer, coc-marksman, coc-sql to auto-install
- Expand optional tools section with stylelint, markdownlint, sqlfluff, marksman

.vimrc

@@ -513,28 +513,35 @@ let g:gitgutter_sign_modified_removed = '~'
 
 " --- ALE (Asynchronous Lint Engine) ---
 let g:ale_linters = {
-\   'python': ['flake8', 'pylint'],
+\   'python':     ['flake8', 'pylint'],
 \   'javascript': ['eslint'],
 \   'typescript': ['eslint', 'tsserver'],
-\   'go': ['gopls', 'golint'],
+\   'go':         ['gopls', 'golint'],
-\   'rust': ['cargo'],
+\   'rust':       ['cargo'],
-\   'sh': ['shellcheck'],
+\   'sh':         ['shellcheck'],
-\   'yaml': ['yamllint'],
+\   'yaml':       ['yamllint'],
 \   'dockerfile': ['hadolint'],
+\   'css':        ['stylelint'],
+\   'scss':       ['stylelint'],
+\   'markdown':   ['markdownlint'],
+\   'sql':        ['sqlfluff'],
 \}
 
 let g:ale_fixers = {
-\   '*': ['remove_trailing_lines', 'trim_whitespace'],
+\   '*':          ['remove_trailing_lines', 'trim_whitespace'],
-\   'python': ['black', 'isort'],
+\   'python':     ['black', 'isort'],
 \   'javascript': ['prettier', 'eslint'],
 \   'typescript': ['prettier', 'eslint'],
-\   'go': ['gofmt', 'goimports'],
+\   'go':         ['gofmt', 'goimports'],
-\   'rust': ['rustfmt'],
+\   'rust':       ['rustfmt'],
-\   'json': ['prettier'],
+\   'json':       ['prettier'],
-\   'yaml': ['prettier'],
+\   'yaml':       ['prettier'],
-\   'html': ['prettier'],
+\   'html':       ['prettier'],
-\   'css': ['prettier'],
+\   'css':        ['prettier'],
-\   'markdown': ['prettier'],
+\   'scss':       ['prettier'],
+\   'less':       ['prettier'],
+\   'markdown':   ['prettier'],
+\   'sql':        ['sqlfmt'],
 \}
 
 " Don't fix on save if LSP is handling formatting (avoids double-format)
@@ -670,12 +677,19 @@ endif
 " --- vim-lsp (Native VimScript LSP - fallback when Node.js unavailable) ---
 if g:use_vimlsp
     " Auto-configure language servers via vim-lsp-settings
-    let g:lsp_settings_filetype_python   = ['pylsp', 'pyright-langserver']
+    let g:lsp_settings_filetype_python     = ['pylsp', 'pyright-langserver']
-    let g:lsp_settings_filetype_go       = ['gopls']
+    let g:lsp_settings_filetype_go         = ['gopls']
-    let g:lsp_settings_filetype_rust     = ['rust-analyzer']
+    let g:lsp_settings_filetype_rust       = ['rust-analyzer']
     let g:lsp_settings_filetype_typescript = ['typescript-language-server']
     let g:lsp_settings_filetype_javascript = ['typescript-language-server']
-    let g:lsp_settings_filetype_sh       = ['bash-language-server']
+    let g:lsp_settings_filetype_sh         = ['bash-language-server']
+    let g:lsp_settings_filetype_html       = ['vscode-html-language-server']
+    let g:lsp_settings_filetype_css        = ['vscode-css-language-server']
+    let g:lsp_settings_filetype_scss       = ['vscode-css-language-server']
+    let g:lsp_settings_filetype_json       = ['vscode-json-language-server']
+    let g:lsp_settings_filetype_yaml       = ['yaml-language-server']
+    let g:lsp_settings_filetype_markdown   = ['marksman']
+    let g:lsp_settings_filetype_sql        = ['sqls']
 
     " Performance: disable virtual text diagnostics in TTY
     let g:lsp_diagnostics_virtual_text_enabled = !g:is_tty

install.sh

@@ -94,9 +94,8 @@ if [ "$HAS_NODE" -eq 1 ]; then
     echo
     if [[ $REPLY =~ ^[Yy]$ ]]; then
         step "Installing CoC language servers"
-        vim +'CocInstall -sync coc-json coc-tsserver coc-pyright coc-sh coc-html coc-css coc-yaml' +qall
+        vim +'CocInstall -sync coc-json coc-tsserver coc-pyright coc-sh coc-html coc-css coc-yaml coc-go coc-rust-analyzer coc-marksman coc-sql' +qall
         ok "CoC language servers installed"
-        echo "  Add more with :CocInstall coc-go coc-rust-analyzer etc."
     fi
 else
     echo "  To enable LSP without Node.js:"
@@ -126,11 +125,15 @@ echo "  ctags  (F8 tag browser)"
 echo "    Ubuntu:  sudo apt install universal-ctags"
 echo "    macOS:   brew install universal-ctags"
 echo ""
-echo "  Language linters:"
+echo "  Language linters and formatters:"
 echo "    Python:      pip install black flake8 pylint isort"
 echo "    JS/TS:       npm install -g prettier eslint typescript"
 echo "    Go:          go install golang.org/x/tools/gopls@latest"
-echo "    Shell:       sudo apt install shellcheck"
+echo "    Shell:       sudo apt install shellcheck  # or: brew install shellcheck"
+echo "    CSS/SCSS:    npm install -g stylelint stylelint-config-standard"
+echo "    Markdown:    npm install -g markdownlint-cli"
+echo "    SQL:         pip install sqlfluff  |  npm install -g sqlfmt"
+echo "    Markdown LS: brew install marksman  # or: https://github.com/artempyanykh/marksman"
 echo ""
 echo "Getting started:"
 echo "  See QUICKSTART.md for the 5-minute guide"