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/components/profile/ProfileTabs.jsx

@@ -0,0 +1,74 @@
+import React, { useEffect, useRef } from 'react'
+
+export const TABS = [
+  { id: 'artworks',    label: 'Artworks',    icon: 'fa-images' },
+  { id: 'posts',       label: 'Posts',       icon: 'fa-newspaper' },
+  { id: 'collections', label: 'Collections', icon: 'fa-layer-group' },
+  { id: 'about',       label: 'About',       icon: 'fa-id-card' },
+  { id: 'stats',       label: 'Stats',       icon: 'fa-chart-bar' },
+  { id: 'favourites',  label: 'Favourites',  icon: 'fa-heart' },
+  { id: 'activity',    label: 'Activity',    icon: 'fa-bolt' },
+]
+
+/**
+ * ProfileTabs
+ * Sticky tab navigation that:
+ *  - Scrolls horizontally on mobile
+ *  - Shows active underline / glow
+ *  - Updates URL query param on tab change
+ */
+export default function ProfileTabs({ activeTab, onTabChange }) {
+  const navRef = useRef(null)
+  const activeRef = useRef(null)
+
+  // Scroll active tab into view on mount/change
+  useEffect(() => {
+    if (activeRef.current && navRef.current) {
+      activeRef.current.scrollIntoView({ behavior: 'smooth', block: 'nearest', inline: 'center' })
+    }
+  }, [activeTab])
+
+  return (
+    <nav
+      ref={navRef}
+      className="profile-tabs-sticky sticky z-30 bg-[#0c1525]/95 backdrop-blur-xl border-b border-white/10 overflow-x-auto scrollbar-hide"
+      aria-label="Profile sections"
+      role="tablist"
+    >
+      <div className="max-w-6xl mx-auto px-3 flex gap-0 min-w-max sm:min-w-0">
+        {TABS.map((tab) => {
+          const isActive = activeTab === tab.id
+          return (
+            <button
+              key={tab.id}
+              ref={isActive ? activeRef : null}
+              onClick={() => onTabChange(tab.id)}
+              role="tab"
+              aria-selected={isActive}
+              aria-controls={`tabpanel-${tab.id}`}
+              className={`
+                relative flex items-center gap-2 px-4 py-3.5 text-sm font-medium whitespace-nowrap
+                transition-colors duration-150 outline-none
+                focus-visible:ring-2 focus-visible:ring-sky-400/70 rounded-t
+                ${isActive
+                  ? 'text-white'
+                  : 'text-slate-400 hover:text-slate-200'
+                }
+              `}
+            >
+              <i className={`fa-solid ${tab.icon} fa-fw text-xs ${isActive ? 'text-sky-400' : ''}`} />
+              {tab.label}
+              {/* Active indicator bar */}
+              {isActive && (
+                <span
+                  className="absolute bottom-0 inset-x-0 h-0.5 rounded-full bg-sky-400 shadow-[0_0_8px_rgba(56,189,248,0.6)]"
+                  aria-hidden="true"
+                />
+              )}
+            </button>
+          )
+        })}
+      </div>
+    </nav>
+  )
+}