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/LLM_REFERENCE.md

@@ -66,7 +66,7 @@ class MainLayout extends Jqhtml_Layout {
   async on_render() {
     this.$.html(`
       <header>Navigation</header>
-      <main $id="content"></main>  <!-- REQUIRED: Routes render here -->
+      <main $sid="content"></main>  <!-- REQUIRED: Routes render here -->
       <footer>Footer</footer>
     `);
   }
@@ -94,7 +94,7 @@ class MainLayout extends Jqhtml_Layout {
 ### Layout Persistence
 - Layouts never re-render during route changes within same layout
 - Layout instance persists until different layout needed
-- `$id="content"` element required for route injection point
+- `$sid="content"` element required for route injection point
 
 ## SPA Application Container
 
@@ -273,7 +273,7 @@ class DashboardRoute extends Jqhtml_Route {
     this.$.html(`
       <div class="dashboard">
         <Sidebar />
-        <div $id="dashboard-content">
+        <div $sid="dashboard-content">
           <!-- Sub-routes could render here -->
         </div>
       </div>
@@ -343,7 +343,7 @@ class SearchRoute extends Jqhtml_Route {
 ```
 
 ## Critical Invariants
-1. Layouts must have element with `$id="content"` for route injection
+1. Layouts must have element with `$sid="content"` for route injection
 2. Route dispatch is asynchronous and can be cancelled at multiple points
 3. Layout instances persist across same-layout route changes
 4. Routes are destroyed and recreated on each navigation