Keep keyboard offsets tied to visibility

Derive app keyboard offsets from one provider-owned shared value so chat content, composer surfaces, and floating panels share the same policy.

Treat progress-zero keyboard samples as closed, even if Android reports a stale nonzero height.

packages/app/src/hooks/use-keyboard-shift-style.test.ts

@@ -0,0 +1,40 @@
+import { describe, expect, it } from "vitest";
+import { resolveKeyboardShift } from "./keyboard-shift-policy";
+
+describe("resolveKeyboardShift", () => {
+  it("keeps the existing open-keyboard offset behavior", () => {
+    expect(
+      resolveKeyboardShift({
+        rawKeyboardHeight: 320,
+        keyboardProgress: 1,
+        bottomInset: 24,
+        isIos: false,
+        iosMinHeight: 120,
+      }),
+    ).toBe(296);
+  });
+
+  it("treats progress zero as closed even when Android reports a stale height", () => {
+    expect(
+      resolveKeyboardShift({
+        rawKeyboardHeight: 320,
+        keyboardProgress: 0,
+        bottomInset: 24,
+        isIos: false,
+        iosMinHeight: 120,
+      }),
+    ).toBe(0);
+  });
+
+  it("still ignores small iOS accessory bar reports", () => {
+    expect(
+      resolveKeyboardShift({
+        rawKeyboardHeight: 80,
+        keyboardProgress: 1,
+        bottomInset: 0,
+        isIos: true,
+        iosMinHeight: 120,
+      }),
+    ).toBe(0);
+  });
+});