docs+consent: disclose activation analytics honestly across consent modal, privacy policy, and store docs (#81)

The app ships PostHog activation-funnel analytics gated behind the same
consent flag as Sentry, but the consent modal, Settings toggle, privacy
policy, and Play Data safety draft only mentioned crash reporting. Fix
the disclosure everywhere:

- TelemetryConsentModal: body + bullets + a11y labels now cover anonymous
  usage analytics (PostHog EU) alongside crash reports
- Settings: toggle renamed 'Crash Reports & Usage Analytics', description
  names both Sentry and PostHog
- Privacy policy (md + html + live gh-pages mirror): new section 3a with
  the full event/property table, PostHog EU destination, anonymous-ID
  statement, decline/revoke (drop-on-revoke) semantics; sections 4-7, 9
  and the Apple nutrition-label addendum updated for analytics
- play-listing.md: Data safety draft declares App interactions + Device
  or other IDs (opt-in, default OFF, shared with PostHog/Sentry)
- docs/playstore.md: Data safety row flipped to re-verify with pointer
  to the new design record
- docs/analytics.md: new design record — event schema, consent gating
  incl. buffered-event drop on revoke, disclosure surfaces to keep in
  sync, verification checklist (all TODO)
- website privacy page metadata mentions analytics opt-in

Closes #63


Claude-Session: https://claude.ai/code/session_01NJKAQ6HAikWGQK7PGZ5Y4E

Co-authored-by: engineer <engineer@gray-knight-m1.local>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

src/lib/i18n/en.json

@@ -29,8 +29,8 @@
     },
     "privacy": {
       "crashReporting": {
-        "label": "Crash Reporting",
-        "description": "Share anonymous crash reports via Sentry to help improve OpenCode. No code or prompts are included."
+        "label": "Crash Reports & Usage Analytics",
+        "description": "Share anonymous crash reports (Sentry) and usage analytics (PostHog) to help improve OpenCode. Diagnostic reports you share are also delivered to our support inbox. No code or prompts are included."
       },
       "privacyPolicy": {
         "label": "Privacy Policy",

src/lib/i18n/zh-Hans.json

@@ -29,8 +29,8 @@
     },
     "privacy": {
       "crashReporting": {
-        "label": "崩溃报告",
-        "description": "通过 Sentry 分享匿名崩溃报告，帮助改进 OpenCode。报告不包含代码或提示词内容。"
+        "label": "崩溃报告与使用分析",
+        "description": "分享匿名崩溃报告（Sentry）和使用分析（PostHog），帮助改进 OpenCode。您分享的诊断报告也会发送至我们的支持收件箱。不包含代码或提示词内容。"
       },
       "privacyPolicy": {
         "label": "隐私政策",