feat: forum rich-text editor, emoji picker, mentions, discover nav, feed, uploads, profile

Forum:
- TipTap WYSIWYG editor with full toolbar
- @emoji-mart/react emoji picker (consistent with tweets)
- @mention autocomplete with user search API
- Fix PHP 8.4 parse errors in Blade templates
- Fix thread data display (paginator items)
- Align forum page widths to max-w-5xl

Discover:
- Extract shared _nav.blade.php partial
- Add missing nav links to for-you page
- Add Following link for authenticated users

Feed/Posts:
- Post model, controllers, policies, migrations
- Feed page components (PostComposer, FeedCard, etc)
- Post reactions, comments, saves, reports, sharing
- Scheduled publishing support
- Link preview controller

Profile:
- Profile page components (ProfileHero, ProfileTabs)
- Profile API controller

Uploads:
- Upload wizard enhancements
- Scheduled publish picker
- Studio status bar and readiness checklist

resources/js/lib/uploadNotices.test.js

@@ -0,0 +1,40 @@
+import { describe, expect, it } from 'vitest'
+import { mapUploadErrorNotice, mapUploadResultNotice } from './uploadNotices'
+
+describe('uploadNotices mapping', () => {
+  it('maps duplicate_hash reason to a clear error message', () => {
+    const notice = mapUploadErrorNotice({
+      response: {
+        status: 409,
+        data: {
+          reason: 'duplicate_hash',
+          message: 'Duplicate upload is not allowed. This file already exists.',
+        },
+      },
+    }, 'Upload failed.')
+
+    expect(notice.type).toBe('error')
+    expect(notice.reason).toBe('duplicate_hash')
+    expect(notice.message).toBe('This file already exists in Skinbase. Please upload a different file.')
+  })
+
+  it('keeps success messages as success', () => {
+    const notice = mapUploadResultNotice({
+      type: 'success',
+      message: 'Artwork published successfully.',
+    })
+
+    expect(notice.type).toBe('success')
+    expect(notice.message).toBe('Artwork published successfully.')
+  })
+
+  it('normalizes warning messages for queued processing', () => {
+    const notice = mapUploadResultNotice({
+      level: 'warning',
+      message: 'Upload received. Processing is queued.',
+    })
+
+    expect(notice.type).toBe('warning')
+    expect(notice.message).toBe('Upload received. Processing is queued.')
+  })
+})