fix(tab-list): strip zero-width unicode from titles (#33); feat(screenshot): --clip pixel region + documented element capture (#34)

#33: some sites prepend runs of ZWJ/word-joiner/invisible-times/BOM to
document.title (badging/anti-scrape); left in, they polluted 'tab list', broke
text matching, and wrecked column alignment. sanitize_title() now strips
zero-width/bidi-format chars at every title ingestion point + get_title().

#34: 'screenshot <selector>' (element capture) already worked but was
undocumented; added 'screenshot --clip x,y,w,h' for an explicit pixel region
(CDP captureScreenshot clip), documented both in --help. Verified live.

cli/src/native/actions.rs

@@ -3000,6 +3000,14 @@ async fn handle_screenshot(cmd: &Value, state: &mut DaemonState) -> Result<Value
             .get("screenshotDir")
             .and_then(|v| v.as_str())
             .map(String::from),
+        clip: cmd.get("clip").and_then(|c| {
+            Some((
+                c.get("x")?.as_f64()?,
+                c.get("y")?.as_f64()?,
+                c.get("width")?.as_f64()?,
+                c.get("height")?.as_f64()?,
+            ))
+        }),
     };
 
     if annotate {
@@ -7446,6 +7454,7 @@ async fn handle_diff_screenshot(cmd: &Value, state: &DaemonState) -> Result<Valu
         quality: None,
         annotate: false,
         output_dir: None,
+        clip: None,
     };
 
     let result = screenshot::take_screenshot(