feat(sidebar): redesign sidebar UI with three user states (light theme)

Replace the dark sidebar theme with a light-themed three-state UI
matching the design references:

- guest  : pink "login" pill in user row, no status pill on VIP card,
           "Activate VIP Membership" button shown
- member : "VIP membership not activated" subtitle, no status pill,
           "Activate VIP Membership" button shown
- vip    : pink "VIP Member" pill with diamond icon, "Activated" pill
           in VIP card header, no Activate button

Decompose into BackBar, UserHeader, VipBenefitsCard, and VoicePackageCard
under src/app/sidebar/components/. Delete obsolete GuestPanel,
UserInfoCard, and VipCta.

Lift VIP_BENEFITS to a shared src/data/constants/vip-benefits.ts so the
sidebar and subscription page render identical benefit copy.

Add five sidebar tokens (--color-card-surface, --color-voice-gradient-*
--border-card, --shadow-card, --color-pill-bg) to src/tokens/colors.css.

Includes barrelsby regeneration for src/app/sidebar/components and
side-effect barrel updates under src/stores/{auth,chat,sidebar,user},
plus package-lock.json from npm install (required for lint/typecheck).

Co-Authored-By: Claude <noreply@anthropic.com>

src/tokens/colors.css

@@ -90,4 +90,21 @@
   --color-settings-divider: #3d314a;
   --color-chevron-icon: #000000;
   --color-destructive: #ff6b6b;
+
+  /* ==================== Sidebar（浅色主题） ==================== */
+  /* 卡片纯白表面 */
+  --color-card-surface: #ffffff;
+
+  /* Voice Message Package 边框/图标渐变（pink → orange） */
+  --color-voice-gradient-start: #ff6fa3;
+  --color-voice-gradient-end: #ff9a5a;
+
+  /* 卡片描边粗细 */
+  --border-card: 1.5px;
+
+  /* 卡片阴影（极轻） */
+  --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.04);
+
+  /* 已激活状态 pill 背景（用于 VIP "Activated" 角标） */
+  --color-pill-bg: rgba(248, 77, 150, 0.10);
 }