Optional app PIN, settings header, pink selection ring

- A PIN (4 to 8 digits, salted SHA-256 in prefs) set in Settings shows
  a logo splash with a PIN prompt at start and whenever the app returns
  after leaving the screen; Back there leaves the app.
- Settings gets the back-arrow header shared with the folder grid
  (Ui.header) and scrolls, since the PIN fields overflow the screen.
- Tile and list focus rings use the icon pink.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/app/src/main/java/mygram/droid/Ui.java b/app/src/main/java/mygram/droid/Ui.java
index 234dad3..172fbff 100644
--- a/app/src/main/java/mygram/droid/Ui.java
+++ b/app/src/main/java/mygram/droid/Ui.java
@@ -14,6 +14,7 @@
 
 package mygram.droid;
 
+import android.app.Activity;
 import android.content.Context;
 import android.graphics.Color;
 import android.graphics.RenderEffect;
@@ -153,6 +154,19 @@ final class Ui {
 		button.getChildAt(1).setVisibility(current ? View.VISIBLE : View.INVISIBLE);
 	}
 
+	/** Back arrow and title, for screens outside the main view. */
+	static LinearLayout header(Activity a, String title) {
+		LinearLayout header = new LinearLayout(a);
+		header.setGravity(Gravity.CENTER_VERTICAL);
+		int p = dp(a, 16);
+		header.setPadding(p * 2, p, p * 2, 0);
+		header.addView(iconButton(a, R.drawable.ic_arrow_back, "Back", v -> a.finish()));
+		TextView t = text(a, title, 24);
+		t.setPadding(p, 0, 0, 0);
+		header.addView(t);
+		return header;
+	}
+
 	static void blur(ImageView v, float radius) {
 		v.setRenderEffect(RenderEffect.createBlurEffect(radius, radius, Shader.TileMode.CLAMP));
 	}