fix(mobile): native keyboard (remove JS hack), open at latest + no double-render dance, splash cfg

- #3 keyboard: the overshoot proved resize:native DOES lift the composer; my --kb JS was a second lift.
  Removed the JS hack entirely; keyboard is now purely @capacitor/keyboard resize:native. Config: turn
  OFF safe-area offsetForKeyboardInsetBug so only one mechanism moves the view (needs the build).
- #7: gate the open-time hide/reveal with _convoRevealed so the cache->network double render doesn't
  flash/dance; on mobile open at the LATEST message (skip auto-scroll to first-unread).
- #6: add SplashScreen config (bg #16294F, no spinner) — asset gen already produces the logo.
Build marker -> 2026-07-18-batch97.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

mobile/capacitor.config.json

@@ -14,10 +14,17 @@
     "SafeArea": {
       "detectViewportFitCoverChanges": true,
       "initialViewportFitCover": true,
-      "offsetForKeyboardInsetBug": true
+      "offsetForKeyboardInsetBug": false
     },
     "Keyboard": {
-      "resize": "none"
+      "resize": "native"
+    },
+    "SplashScreen": {
+      "launchShowDuration": 900,
+      "launchAutoHide": true,
+      "backgroundColor": "#16294F",
+      "showSpinner": false,
+      "iosSpinnerStyle": "large"
     }
   }
 }