fix(android): harden origin isolation and native file lifecycles

Block cross-origin POSTs, preserve bounded generated exports without relaxing CSP, bind picker results to their initiating context, erase camera cache and constrain platform permissions. Upgrade vulnerable build/test tooling and lock runtime/build dependencies. JVM regressions, lint and unsigned release builds pass; extended emulator validation remains separate.

android/app/src/main/java/community/yuvomi/mobile/SelectionGate.kt

@@ -0,0 +1,23 @@
+package community.yuvomi.mobile
+
+/** Never delivers a late system-picker result into a different server/web context. */
+class SelectionGate {
+    private var owner: Int? = null
+    val outstanding: Boolean get() = owner != null
+
+    fun begin(generation: Int): Boolean {
+        if (outstanding) return false
+        owner = generation
+        return true
+    }
+
+    fun consume(generation: Int): Boolean {
+        val previous = owner
+        owner = null
+        return previous == generation
+    }
+
+    fun restoreOutstanding() {
+        owner = -1
+    }
+}