feat: upload wizard refactor + vision AI tags + artwork versioning

Upload wizard:
- Refactored UploadWizard into modular steps (Step1FileUpload, Step2Details, Step3Publish)
- Extracted reusable hooks: useUploadMachine, useFileValidation, useVisionTags
- Extracted reusable components: CategorySelector, ContentTypeSelector
- Added TagPicker component (studio-style list picker with AI badge + new-tag insertion)
- Fixed TagInput auto-open bug (hasFocusedRef guard)
- Replaced TagInput with TagPicker in UploadSidebar

Vision AI tag suggestions:
- Add UploadVisionSuggestController: sync POST /api/uploads/{id}/vision-suggest
- Calls vision.klevze.net/analyze/all on upload completion (before step 2 opens)
- Two-phase useVisionTags: immediate gateway call + background DB polling
- Trigger fires on uploadReady (not step change) so tags arrive before user sees step 2
- Added vision.gateway config block with VISION_GATEWAY_URL env

Artwork versioning system:
- ArtworkVersion / ArtworkVersionEvent models
- ArtworkVersioningService: createNewVersion, restoreVersion, rate limiting, ranking decay
- Migrations: artwork_versions, artwork_version_events, versioning columns on artworks
- Studio API routes: GET versions, POST restore/{version_id}
- Feature tests: ArtworkVersioningTest (13 cases)

app/Models/ArtworkVersion.php

@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+/**
+ * App\Models\ArtworkVersion
+ *
+ * Represents a single immutable snapshot of an artwork file.
+ * Only one version per artwork is marked is_current = true at a time.
+ */
+class ArtworkVersion extends Model
+{
+    protected $table = 'artwork_versions';
+
+    protected $fillable = [
+        'artwork_id',
+        'version_number',
+        'file_path',
+        'file_hash',
+        'width',
+        'height',
+        'file_size',
+        'change_note',
+        'is_current',
+    ];
+
+    protected $casts = [
+        'is_current'  => 'boolean',
+        'version_number' => 'integer',
+        'width'       => 'integer',
+        'height'      => 'integer',
+        'file_size'   => 'integer',
+    ];
+
+    public function artwork(): BelongsTo
+    {
+        return $this->belongsTo(Artwork::class);
+    }
+}