fix(lsp): add Push model support and fix JSON LSP diagnostics

- Add diagnosticsStore to capture Push model notifications
- Handle textDocument/publishDiagnostics notifications in processBuffer
- Fix workspace/configuration response for JSON LSP validation
- Add missing language mappings (json, html, css, sh, fish, md, tf)
- diagnostics() now tries Pull first, falls back to Push store

src/tools/lsp/constants.ts

@@ -175,4 +175,18 @@ export const EXT_TO_LANG: Record<string, string> = {
   ".astro": "astro",
   ".yaml": "yaml",
   ".yml": "yaml",
+  ".json": "json",
+  ".jsonc": "jsonc",
+  ".html": "html",
+  ".htm": "html",
+  ".css": "css",
+  ".scss": "scss",
+  ".less": "less",
+  ".sh": "shellscript",
+  ".bash": "shellscript",
+  ".zsh": "shellscript",
+  ".fish": "fish",
+  ".md": "markdown",
+  ".tf": "terraform",
+  ".tfvars": "terraform",
 }