refactor: remove legacy HeroSection component (orphaned code)

BREAKING: Remove unused HeroSectionRenderer and content-hero template

Analysis confirmed HeroSection was legacy orphaned code:
- No JSON schema (hero-section.json didn't exist)
- No FormBuilder for admin UI
- No database records (component_name='hero-section')
- No template usage (single.php uses 'hero' not 'hero-section')
- Violated Clean Architecture (hardcoded CSS)

Removed files:
- Public/HeroSection/Infrastructure/Ui/HeroSectionRenderer.php
- TemplateParts/content-hero.php
- case 'hero-section' from functions-addon.php switch

Active Hero component (Schemas/hero.json + HeroRenderer.php) remains unchanged.

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

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

functions-addon.php

@@ -297,9 +297,6 @@ function roi_render_component(string $componentName): string {
             case 'cta-lets-talk':
                 $renderer = new \ROITheme\Public\CtaLetsTalk\Infrastructure\Ui\CtaLetsTalkRenderer($cssGenerator);
                 break;
-            case 'hero-section':
-                $renderer = new \ROITheme\Public\HeroSection\Infrastructure\Ui\HeroSectionRenderer();
-                break;
             case 'featured-image':
                 $renderer = new \ROITheme\Public\FeaturedImage\Infrastructure\Ui\FeaturedImageRenderer($cssGenerator);
                 break;