feat(contacts): animated avatars (GIF/WebP) with a Settings toggle

Animate contact avatars end to end:

- texture_loader gains LoadAnimatedRGBA: decodes an image into a downscaled
  RGBA frame sequence + per-frame durations — animated GIF via stb
  (stbi_load_gif_from_memory) and animated WebP via libwebp's WebPAnimDecoder;
  stills (and APNG, which stb reads as one image) return a single frame. Frames
  are box-downscaled (smaller cap for animations) to bound VRAM, capped at 300.
- The contacts avatar cache now holds a frame sequence; currentAvatarFrame()
  advances animated avatars by the ImGui clock and is used everywhere avatars
  draw (list, cards, table, grid, preview). When a live animated frame is drawn
  it flags the render loop (ConsumeContactsAvatarAnimation, clear-on-read) so
  main.cpp keeps producing frames while animation plays and idles when it stops
  or the contacts view is hidden.
- New animate_avatars setting (default on) + a Settings appearance toggle
  ("Animate avatars"); off shows the first frame only. currentAvatarFrame
  honors it. +i18n (8 langs, CJK subset rebuilt for 帧/播/첫).

Verified: a 3-frame GIF and a 3-frame animated WebP both decode to 3 frames
with correct 120ms delays through the exact libwebp/stb calls used here.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/config/settings.h

@@ -187,6 +187,9 @@ public:
     // Contacts tab address-list view: 0 = cards, 1 = list, 2 = table.
     int getContactsViewMode() const { return contacts_view_mode_; }
     void setContactsViewMode(int v) { contacts_view_mode_ = (v < 0 || v > 2) ? 0 : v; }
+    // Play animated contact avatars (GIF/WebP). Off = show the first frame only.
+    bool getAnimateAvatars() const { return animate_avatars_; }
+    void setAnimateAvatars(bool v) { animate_avatars_ = v; }
 
     // Console scanline effect
     bool getScanlineEnabled() const { return scanline_enabled_; }
@@ -494,6 +497,7 @@ private:
     std::string balance_layout_ = "classic";
     int portfolio_style_ = 0;   // Market portfolio row style (0 single / 1 two-line / 2 hero)
     int contacts_view_mode_ = 0;   // Contacts address-list view (0 cards / 1 list / 2 table)
+    bool animate_avatars_ = true;  // play animated (GIF/WebP) contact avatars
     bool scanline_enabled_ = true;
     bool console_line_accents_ = true;   // left color accent bars in console output
     bool console_text_color_ = true;     // per-channel text coloring in console output