chore: prepare desktop 0.15.10 release

Document unified navigation, Supervisor controls, activity and desktop performance changes. Keep Agent 0.15.3 and record schema 58 backup requirements, NORMAL durability tradeoffs, and bounded real Host evidence.

FEATURES.md

@@ -345,7 +345,7 @@ records are listed separately and do not introduce another feature status.
   failure, Agent `SIGKILL`/restart, and recovery from a reopened Desktop SQLite
   database. Successful tool START/END events appear exactly once, with no
   Prompt, provider, or tool replay observed. The current Agent source lock is
-  `0.15.3`, paired with the current Desktop release candidate `0.15.9`; formal
+  `0.15.3`, paired with the current Desktop release candidate `0.15.10`; formal
   publication status follows the separate Agent and Desktop
   release channels. Previous macOS validation covered native package installation,
   detached lifecycle, Attach, real Ask/Execute, and cancellation of tools in
@@ -978,9 +978,22 @@ records are listed separately and do not introduce another feature status.
 
 ### Open source, builds, and releases
 
-- The current Desktop candidate is `0.15.9`; Agent candidate `0.15.3` requires Desktop `0.15.9`, with
+- The current Desktop candidate is `0.15.10`; published Agent `0.15.3` requires Desktop `0.15.9`, with
   OpenCode pinned to `1.18.29` and Continue to `1.5.47`. Publication status follows the independent
   Desktop and Agent release channels.
+- Desktop `0.15.10` unifies project/conversation navigation with ten recent
+  conversations, adds independent Supervisor model selection and a default-on
+  per-conversation Story Graph switch. Indexed activity paging and complete
+  summaries, document Workers, lazy startup, narrower render subscriptions,
+  windowed lists, terminal batching and old Runtime cache cleanup reduce repeated
+  work without promising universal speedups. Schema 58 requires a pre-upgrade
+  database and notes backup. Frequent local writes use NORMAL and can lose a
+  recent suffix on power/system failure; remote acknowledgments, channel delivery
+  and task lifecycle writes retain FULL. Agent stays at 0.15.3. Four real Host
+  model requests and a 1,000-line Unicode SSH terminal check passed; exact-source
+  CI and six native packages remain release gates, and reported remote resume
+  failures are not claimed fixed. See the
+  [preparation record](./docs/development/release-preparation-0.15.10.md).
 - Desktop `0.15.9` adds shared review progress, stories, experiences, and spiral
   graph navigation, with schema 56 backup/rollback requirements and possible
   model costs. Conversation/message windowing, Markdown caching, read-only