Rewrite X11 backend to drop xcap

Use x11rb directly for screenshot capture and window metadata so the Linux build no longer drags in Wayland build dependencies.

Co-authored-by: Codex <noreply@openai.com>

src/core/protocol.rs

@@ -21,10 +21,14 @@ pub struct Response {
 impl Request {
     pub fn new(action: &str) -> Self {
         Self {
-            id: format!("r{}", std::time::SystemTime::now()
-                .duration_since(std::time::UNIX_EPOCH)
-                .unwrap_or_default()
-                .as_micros() % 1_000_000),
+            id: format!(
+                "r{}",
+                std::time::SystemTime::now()
+                    .duration_since(std::time::UNIX_EPOCH)
+                    .unwrap_or_default()
+                    .as_micros()
+                    % 1_000_000
+            ),
             action: action.to_string(),
             extra: Value::Object(serde_json::Map::new()),
         }
@@ -40,10 +44,18 @@ impl Request {
 
 impl Response {
     pub fn ok(data: Value) -> Self {
-        Self { success: true, data: Some(data), error: None }
+        Self {
+            success: true,
+            data: Some(data),
+            error: None,
+        }
     }
 
     pub fn err(msg: impl Into<String>) -> Self {
-        Self { success: false, data: None, error: Some(msg.into()) }
+        Self {
+            success: false,
+            data: None,
+            error: Some(msg.into()),
+        }
     }
 }

src/core/refs.rs

@@ -1,5 +1,5 @@
-use std::collections::HashMap;
 use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[allow(dead_code)]
@@ -26,7 +26,10 @@ pub struct RefMap {
 #[allow(dead_code)]
 impl RefMap {
     pub fn new() -> Self {
-        Self { map: HashMap::new(), next_ref: 1 }
+        Self {
+            map: HashMap::new(),
+            next_ref: 1,
+        }
     }
 
     pub fn clear(&mut self) {
@@ -57,16 +60,14 @@ impl RefMap {
         // Try substring match on app_class or title (case-insensitive)
         let lower = selector.to_lowercase();
         self.map.values().find(|e| {
-            e.app_class.to_lowercase().contains(&lower)
-                || e.title.to_lowercase().contains(&lower)
+            e.app_class.to_lowercase().contains(&lower) || e.title.to_lowercase().contains(&lower)
         })
     }
 
     /// Resolve a selector to the center coordinates of the window.
     pub fn resolve_to_center(&self, selector: &str) -> Option<(i32, i32)> {
-        self.resolve(selector).map(|e| {
-            (e.x + e.width as i32 / 2, e.y + e.height as i32 / 2)
-        })
+        self.resolve(selector)
+            .map(|e| (e.x + e.width as i32 / 2, e.y + e.height as i32 / 2))
     }
 
     pub fn entries(&self) -> impl Iterator<Item = (&String, &RefEntry)> {