Fix code quality violations for publish

Remove unused blade settings pages not linked from UI
Convert remaining frontend pages to SPA actions
Convert settings user_settings and general to SPA actions
Convert settings profile pages to SPA actions
Convert contacts and projects add/edit pages to SPA actions
Convert clients add/edit page to SPA action with loading pattern
Refactor component scoped IDs from $id to $sid
Fix jqhtml comment syntax and implement universal error component system
Update all application code to use new unified error system
Remove all backwards compatibility - unified error system complete
Phase 5: Remove old response classes
Phase 3-4: Ajax response handler sends new format, old helpers deprecated
Phase 2: Add client-side unified error foundation
Phase 1: Add server-side unified error foundation
Add unified Ajax error response system with constants

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

node_modules/@jqhtml/router/dist/index.js

@@ -878,7 +878,7 @@ class Jqhtml_Layout extends Jqhtml_Component {
      * Must contain an element with $id="content"
      */
     $content() {
-        const $content = this.$id('content');
+        const $content = this.$sid('content');
         if (!$content.length) {
             throw new Error(`Layout ${this.constructor.name} must have an element with $id="content"`);
         }