chore(launch): reconcile README/store live-status + add demo-funnel analytics (#111)

Two scoped changes for the no-spend growth launch (Growth Launch Kit,
Notion page 3a1ac25eb49f81099cc9f3a4286c8ec4):

1. README.md and distribution/play-listing.md said Google Play was
   "coming soon" / internal-testing-only, while distribution/retention-analysis.md
   and the live play.google.com listing show it's actually public with 1K+
   installs. Fixed the contradiction, added Google Play as a third install
   channel, and added an accurate mention of the new offline demo mode
   ("Try a Demo" — reasoning, grep, diff, permission prompt, ~30s, no server)
   matching what app/demo.tsx + src/lib/demo-script.ts actually render.
   play-listing.md's stale pre-launch checklists are marked historical
   instead of rewritten, so #83's ASO copy/keyword work is untouched.

2. Added the demo funnel's key metric (demo-completion, per the launch
   kit) as four consent-gated PostHog events: demo_started,
   demo_step_advanced, demo_completed, demo_exited_to_connect. Pure
   property-derivation logic lives in src/lib/demo-analytics.ts (no
   RN/PostHog imports, unit-tested with node --test, same pattern as
   analytics-classify.ts) and is wired into app/demo.tsx's lifecycle.
   Updated docs/analytics.md's event table and the privacy policy's event
   list (distribution/privacy-policy.md + its two HTML mirrors) per the
   repo's "new event requires a policy update" convention.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

docs/privacy/index.html

@@ -95,7 +95,7 @@
 <header>
   <h1>OpenCode Mobile — Privacy Policy</h1>
   <p class="meta">
-    Effective date: 2026-05-24 &nbsp;|&nbsp;
+    Effective date: 2026-07-18 &nbsp;|&nbsp;
     Operator: VIBE TECHNOLOGIES, LLC &nbsp;|&nbsp;
     App: OpenCode Mobile (<code>cc.agentlabs.opencode</code>)
   </p>
@@ -239,6 +239,27 @@
       <td>An agent response finishes</td>
       <td>—</td>
     </tr>
+    <tr>
+      <td><code>demo_started</code></td>
+      <td>You open the offline "Try a Demo" screen (no server, no network)</td>
+      <td>—</td>
+    </tr>
+    <tr>
+      <td><code>demo_step_advanced</code></td>
+      <td>You reply to the demo's scripted permission prompt</td>
+      <td><code>step_index</code>, <code>step_name</code>, <code>reply</code> ("once", "always", or
+          "reject")</td>
+    </tr>
+    <tr>
+      <td><code>demo_completed</code></td>
+      <td>The scripted demo reaches its end</td>
+      <td><code>outcome</code> ("completed" or "denied")</td>
+    </tr>
+    <tr>
+      <td><code>demo_exited_to_connect</code></td>
+      <td>You tap "Connect your own server" on the demo's CTA</td>
+      <td><code>reached_completion</code> (true/false)</td>
+    </tr>
   </tbody>
 </table>
 
@@ -246,7 +267,8 @@
   What analytics events <strong>never</strong> contain: your server URL, hostname, IP address,
   or port; prompts, messages, or AI responses; code or file contents; tokens or credentials;
   raw error messages. Connection failures are reduced to a fixed list of coarse categories
-  before being sent.
+  before being sent. The demo screen is fully offline and hardcoded — these events describe
+  interaction with the scripted walkthrough, never real session content.
 </p>
 <p>
   Analytics data is sent to PostHog's <strong>EU region</strong> (<code>eu.i.posthog.com</code>)
@@ -469,7 +491,7 @@
 
 <footer>
   &copy; 2026 VIBE TECHNOLOGIES, LLC. OpenCode Mobile is MIT-licensed open-source software.
-  Privacy policy effective 2026-05-24.<br>
+  Privacy policy effective 2026-07-18.<br>
   <a href="https://dzianisv.github.io/opencode-mobile/">Home</a> &middot;
   <a href="https://dzianisv.github.io/opencode-mobile/guide/">Setup guide</a> &middot;
   <a href="https://github.com/dzianisv/opencode-mobile">GitHub</a>