Touch interface for phones and tablets; category toolbar for mouse and touch

- touch.rs: gesture recognition (tap, double tap, long press, drag, two-finger pan/pinch/rotate)
- Touch mode: Auto (touch device or first touch) / On / Off in Settings -> Game
- Larger interface factor on touch screens, top bar wraps, smaller minimap, fewer messages
- Toolbar grouped into categories with pop-up rows and a menu button, also on the desktop
- Long press shows information or drops held units; double tap with the hand slaps
- Savegame name via the browser's text dialog when the name field is tapped
- Touch help texts (EN/DE)

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

src/platform.rs

@@ -14,6 +14,8 @@ mod imp {
     extern "C" {
         fn dc_storage_get(key: *const u8, key_len: u32) -> i32;
         fn dc_storage_take(dst: *mut u8);
+        fn dc_coarse_pointer() -> i32;
+        fn dc_prompt(t: *const u8, tl: u32, d: *const u8, dl: u32) -> i32;
         fn dc_storage_set(key: *const u8, key_len: u32, val: *const u8, val_len: u32);
         fn dc_cache_set(key: *const u8, key_len: u32, val: *const u8, val_len: u32);
         fn dc_download(name: *const u8, name_len: u32, data: *const u8, data_len: u32);
@@ -55,6 +57,24 @@ mod imp {
         }
     }
 
+    // phones and tablets: the main pointer is a finger
+    pub fn coarse_pointer() -> bool {
+        unsafe { dc_coarse_pointer() != 0 }
+    }
+
+    // asks for a text with the browser's dialog; None when cancelled
+    pub fn prompt(title: &str, default: &str) -> Option<String> {
+        unsafe {
+            let n = dc_prompt(title.as_ptr(), title.len() as u32, default.as_ptr(), default.len() as u32);
+            if n < 0 {
+                return None;
+            }
+            let mut buf = vec![0u8; n as usize];
+            dc_storage_take(buf.as_mut_ptr());
+            String::from_utf8(buf).ok()
+        }
+    }
+
     pub fn storage_set(key: &str, val: &str) {
         unsafe { dc_storage_set(key.as_ptr(), key.len() as u32, val.as_ptr(), val.len() as u32) }
     }
@@ -96,6 +116,12 @@ mod imp {
     pub fn storage_get(key: &str) -> Option<String> {
         STORE.with(|s| s.borrow().get(key).cloned())
     }
+    pub fn prompt(_title: &str, _default: &str) -> Option<String> {
+        None
+    }
+    pub fn coarse_pointer() -> bool {
+        false
+    }
     pub fn storage_set(key: &str, val: &str) {
         STORE.with(|s| s.borrow_mut().insert(key.to_string(), val.to_string()));
     }