refactor: restructure dashboard UX and migrate logos to provider level

- Move job submission form to separate view (?action=new_job)
- Replace inline form with prominent green button on main dashboard
- Migrate logos from per-job (post thumbnail) to per-provider (user meta)
- Add logo upload/removal functionality to provider dashboard
- Display provider logo on single job pages instead of per-job logo
- Add back link to archive on single job pages
- Remove logo handling from form submission/edit processors
- Improve button styling with proper CSS specificity

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

includes/class-template.php

@@ -40,7 +40,8 @@ class DDHH_JM_Template {
 		$job_type          = get_post_meta( $post->ID, 'job_type', true );
 		$job_deadline      = get_post_meta( $post->ID, 'job_deadline', true );
 		$job_contact_email = get_post_meta( $post->ID, 'job_contact_email', true );
-		$job_logo          = get_the_post_thumbnail( $post->ID, 'job-logo' );
+		$provider_logo_id  = get_user_meta( $post->post_author, 'ddhh_provider_logo', true );
+		$job_logo          = $provider_logo_id ? wp_get_attachment_image( absint( $provider_logo_id ), 'job-logo' ) : '';
 
 		// Get author/organization info
 		$author      = get_userdata( $post->post_author );
@@ -50,6 +51,9 @@ class DDHH_JM_Template {
 		// Build job details HTML
 		ob_start();
 		?>
+		<div class="ddhh-back-to-archive">
+			<a href="<?php echo esc_url( get_post_type_archive_link( 'job_offer' ) ); ?>">← Alle Jobangebote</a>
+		</div>
 		<div class="ddhh-job-offer-details">
 			<?php if ( $job_logo ) : ?>
 				<div class="job-logo">
@@ -118,6 +122,18 @@ class DDHH_JM_Template {
 			<?php endif; ?>
 
 			<style>
+				.ddhh-back-to-archive {
+					margin-bottom: 1.5rem;
+				}
+				.ddhh-back-to-archive a {
+					color: #3b82f6;
+					text-decoration: none;
+					font-weight: 500;
+				}
+				.ddhh-back-to-archive a:hover {
+					color: #2563eb;
+					text-decoration: underline;
+				}
 				.ddhh-job-offer-details {
 					margin: 2em 0;
 				}