perf(editor): eliminate two-way controller bouncing and full-string comparisons in QueryaCodeEditor #1352

Summary

In lib/core/editor/querya_code_editor.dart (lines 103–127, 181–185):
When an external controller is provided (e.g. from SqlQueryTabSession), QueryaCodeEditor instantiates an internal _highlightController (QueryaHighlightController) and wires up two-way listeners:

• external.addListener(_syncFromExternal)
• _highlightController.addListener(_syncToExternal)

Both callbacks perform full string comparisons:

if (external.text == highlight.text && external.selection == highlight.selection) {
  return;
}

Whenever the user types a single character:

1. _highlightController notifies listeners.
2. _syncToExternal runs and compares external.text == highlight.text (full string comparison of the entire document).
3. If unequal, external.value = highlight.value.
4. external notifies its listeners.
5. _syncFromExternal runs and compares external.text == highlight.text again.

In medium to large SQL scripts (e.g. 50–500 KB), typing a single character triggers repeated multi-kilobyte string comparisons on the main UI thread.

Proposed Solution

1. Allow QueryaCodeEditor to share the controller directly or allow SqlQueryTabSession to create a QueryaHighlightController directly.
2. If two-way sync is retained for plain external controllers, track version/revision tokens or listen directly without comparing entire document strings on every keystroke.

Acceptance Criteria

• No full-document string equality checks (external.text == highlight.text) on every keystroke in QueryaCodeEditor.
• Synchronization between SqlQueryTabSession.controller and the editor remains consistent without text loss or cursor jumping.