refactor(lsp): restructure lsp plugin controller architecture and simplify provider cache

- Replace LSPManager usage with LSPController integration
- Move UI access through lsp_controller.lsp_manager_ui
- Remove legacy ProviderResponseCache client management
- Simplify completion filtering and matcher handling
- Improve typing annotations and modernize union syntax
- Clean up unused imports and dead code
- Fix completion item parsing for insertText/textEdit fallbacks
- Add async-safe scrolling via GLib.idle_add

plugins/code/ui/lsp_manager/handlers/default.py

@@ -0,0 +1,100 @@
+# Python imports
+
+# Lib imports
+
+# Application imports
+from libs.event_factory import Event_Factory, Code_Event_Types
+
+from .base import BaseHandler
+
+
+
+class DefaultHandler(BaseHandler):
+    """Fallback handler for unknown languages - uses generic LSP handling."""
+
+    def handle(self, method: str, response, controller):
+        match method:
+            case "textDocument/completion":
+                self._handle_completion(response)
+            case "textDocument/definition":
+                self._handle_definition(response, controller)
+            case "textDocument/publishDiagnostics":
+                self._handle_diagnostics(response)
+
+    def _handle_completion(self, result):
+        if not result: return
+
+        items = result.get("items", []) if isinstance(result, dict) else result
+
+        self.response_cache.matchers.clear()
+        for item in items:
+            label = item.get("label")
+            if not label:
+                continue
+
+            text = (
+                item.get("insertText")
+                or item.get("textEdit", {}).get("newText")
+                or item.get("textEditText", "")
+                or label
+            )
+
+            detail = item.get("detail")
+            doc    = item.get("documentation")
+
+            if detail:
+                info = detail
+            elif isinstance(doc, dict):
+                info = doc.get("value", "")
+            else:
+                info = str(doc) if doc else ""
+
+            self.response_cache.matchers[label] = {
+                "label": label,
+                "text": text,
+                "info": info,
+            }
+
+        self.context._prompt_completion_request()
+
+    def _handle_definition(self, response, controller):
+        if not response: return
+
+        uri = response[0]["uri"]
+        self.context._prompt_goto_request(uri, response[0]["range"])
+
+    def _handle_diagnostics(self, params):
+        if not params: return
+
+        uri = params.get("uri", "")
+        diagnostics = params.get("diagnostics", [])
+
+        errors   = []
+        warnings = []
+        hints    = []
+
+        for diag in diagnostics:
+            severity  = diag.get("severity", 1)
+            message   = diag.get("message", "")
+            range     = diag.get("range", {})
+
+            diag_info = {
+                "message": message,
+                "range": range
+            }
+
+            if severity == 1:
+                errors.append(diag_info)
+            elif severity == 2:
+                warnings.append(diag_info)
+            elif severity == 3:
+                hints.append(diag_info)
+
+        self.response_cache.lsp_diagnostics = {
+            "uri":      uri,
+            "errors":   errors,
+            "warnings": warnings,
+            "hints":    hints
+        }
+
+        logger.debug(f"LSP Diagnostics for {uri}: {len(errors)} errors, {len(warnings)} warnings, {len(hints)} hints")