docs: flip FoF section 20a badges to v0.7.0 + sessions.md release entry

design.html section 20a (Friend-of-Friend Visibility):
- Section header badge: planned → v0.7.0 complete
- FoFClosed PostVisibility table row: planned → v0.7.0
- All 5 layer rows in the implementation table: planned → v0.7.0
- Custom-subset row retained as v2 (genuinely deferred per spec)

sessions.md: full session entry for the Layer 1-5 implementation arc.
34 commits, ~24 new fof:: integration tests, key design decisions
preserved (slot_binder_nonce circularity fix, per-post pub_x/priv_x,
multi-epoch receiver-chain V_me storage, retroactive cascade delete,
key-burn semantics).

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

website/design.html

@@ -1305,7 +1305,7 @@ END</code></pre>
                 <tr><td><code>Public</code></td><td>None</td><td>Unlimited</td></tr>
                 <tr><td><code>Encrypted { recipients }</code></td><td>~60 bytes per recipient</td><td>~500 (256KB cap)</td></tr>
                 <tr><td><code>GroupEncrypted { group_id, epoch, wrapped_cek }</code></td><td>~100 bytes total</td><td>Unlimited (one CEK wrap for the group)</td></tr>
-                <tr><td><code>FoFClosed { pub_post_set, wrap_slots }</code> <span class="badge badge-planned">Planned</span></td><td>~154 bytes per admitted V_x, padded</td><td>Bucketed (8/16/32/64/128/256, then +128 steps)</td></tr>
+                <tr><td><code>FoFClosed</code> <span class="badge badge-complete">v0.7.0</span></td><td>~154 bytes per admitted V_x, padded</td><td>Bucketed (8/16/32/64/128/256, then +128 steps)</td></tr>
             </table>
 
             <h3>PostId integrity</h3>
@@ -1354,7 +1354,7 @@ END</code></pre>
 
         <!-- 20a. Friend-of-Friend Visibility -->
         <section id="fof">
-            <h2>20a. Friend-of-Friend Visibility <span class="badge badge-planned">Planned</span></h2>
+            <h2>20a. Friend-of-Friend Visibility <span class="badge badge-complete">v0.7.0</span></h2>
 
             <div class="note">
                 <strong>Distinct from directory vouches.</strong> The "FoF vouch" described here is a <em>cryptographic</em> primitive for post readership and comment gating (per-persona symmetric key <code>V_me</code>). It is unrelated to the <em>directory vouch</em> system in <a href="#directory">section 27</a>, which governs discovery-layer trust and bot-ring resistance. The two share vocabulary but operate at different layers.
@@ -1443,11 +1443,11 @@ END</code></pre>
             <p>Full crypto-level byte layouts, data models, wire-format additions, ship criteria, and integration tests are specified in <code>docs/fof-spec/</code>. The implementation is layered for bottom-up shipping:</p>
             <table>
                 <tr><th>Layer</th><th>Scope</th><th>Status</th></tr>
-                <tr><td>1</td><td>Vouch primitive (V_x keys, keyring, bio-post HPKE wrappers, scan policy)</td><td><span class="badge badge-planned">Planned</span></td></tr>
-                <tr><td>2</td><td>Mode 2: public posts with FoF-gated comments, CDN-level verification</td><td><span class="badge badge-planned">Planned</span></td></tr>
-                <tr><td>3</td><td>Mode 1: <code>FoFClosed</code> body + wrap slots + anonymous prefilter</td><td><span class="badge badge-planned">Planned</span></td></tr>
-                <tr><td>4</td><td>Rotation, revocation, key lifecycle (grandfather + cascade + key-burn)</td><td><span class="badge badge-planned">Planned</span></td></tr>
-                <tr><td>5</td><td>Unlock cache + prefilter optimization (perf-critical at scale)</td><td><span class="badge badge-planned">Planned</span></td></tr>
+                <tr><td>1</td><td>Vouch primitive (V_x keys, keyring, bio-post HPKE wrappers, scan policy)</td><td><span class="badge badge-complete">v0.7.0</span></td></tr>
+                <tr><td>2</td><td>Mode 2: public posts with FoF-gated comments, CDN-level verification</td><td><span class="badge badge-complete">v0.7.0</span></td></tr>
+                <tr><td>3</td><td>Mode 1: <code>FoFClosed</code> body + wrap slots + anonymous prefilter</td><td><span class="badge badge-complete">v0.7.0</span></td></tr>
+                <tr><td>4</td><td>Rotation, revocation, key lifecycle (grandfather + cascade + key-burn)</td><td><span class="badge badge-complete">v0.7.0</span></td></tr>
+                <tr><td>5</td><td>Unlock cache + prefilter optimization (perf-critical at scale)</td><td><span class="badge badge-complete">v0.7.0</span></td></tr>
             </table>
         </section>