feat: streamer profile header — modern channel-page card above VOD grid

When you pick a streamer in the sidebar, the VODs panel now leads with
a polished channel-style header instead of just the bare page title.
This is the "personal" feel — you are looking at a creator, not a folder.

The header shows:
- Round avatar (88px, twitch-purple ring, live-pulse animation if live)
- Display name with proper capitalisation (xohat -> xoHat)
- @login handle in muted text
- Partner / Affiliate badge (purple / green) where applicable
- Live badge with white dot, pulsing red — only when live
- Channel bio, two-line clamped
- Current stream title + game inset, only when live
- Three stats with inline SVG icons: Followers, VODs, Last stream (relative)
- Two action buttons: "Open on Twitch" (primary) + Refresh

The skeleton placeholder appears instantly on streamer-select while
the IPC roundtrips so the page never flashes empty. Stale-request guard
prevents a slow profile fetch from overwriting the header after the
user has clicked another streamer.

Backend (main.ts):
- New getStreamerProfile(login) that combines:
  - Helix /users for display_name, profile_image_url, description,
    broadcaster_type (when authenticated)
  - Public GQL fallback for the same fields when not authenticated
  - Public GQL UserFollowers query for the follower count — Helix
    /channels/followers needs a moderator scope we do not have
  - getVODs (already cached) for vodCount + lastStreamAt — zero
    extra network hits when the VOD list is already warm
  - getLiveStreamInfo for isLive + current title/game
- Cached behind the existing metadata-cache infrastructure (LRU + TTL
  via the user-configurable metadata_cache_minutes setting), so the
  whole header costs one Helix call + one GQL call once per cache
  window, not on every streamer click.

Frontend:
- New renderer-profile.ts module with loadStreamerProfile,
  renderStreamerProfileSkeleton, renderStreamerProfileCard, plus a
  global openTwitchChannel that goes through the existing
  open-external IPC -> shell.openExternal pipeline.
- Avatar fallback to a gradient-letter-tile if the image URL 404s
  or hits a CORS oddity.
- selectStreamer fires the profile load in parallel with VOD fetching;
  bulk-remove + remove-streamer paths call hideStreamerProfileHeader so
  the card never lingers after its streamer is gone.

CSS adds the .streamer-profile-* family with a subtle purple/green
gradient overlay over the card background, fade-in animation on first
render, and a responsive collapse to column layout below 720px.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/index.html

@@ -280,6 +280,7 @@
             <div class="content">
                 <!-- VODs Tab -->
                 <div class="tab-content active" id="vodsTab">
+                    <div id="streamerProfileHeader" class="streamer-profile-header" style="display:none;"></div>
                     <div class="vod-filter-row" style="display:flex; align-items:center; gap:8px; margin-bottom:12px; flex-wrap:wrap;">
                         <input type="text" id="vodFilterInput" placeholder="Filter VODs..." oninput="onVodFilterInput()" style="flex:1; min-width:180px; background: var(--bg-card); border:1px solid var(--border-soft); border-radius:6px; padding:8px 12px; color: var(--text); font-size:13px;">
                         <button id="vodFilterClearBtn" onclick="clearVodFilter()" title="Clear filter" style="display:none; background:transparent; border:1px solid var(--border-soft); border-radius:6px; padding:8px 12px; color: var(--text-secondary); cursor:pointer;">x</button>
@@ -840,6 +841,7 @@
     <script src="../dist/renderer-updates.js"></script>
     <script src="../dist/renderer-stats.js"></script>
     <script src="../dist/renderer-archive.js"></script>
+    <script src="../dist/renderer-profile.js"></script>
     <script src="../dist/renderer.js"></script>
 </body>
 </html>