Add bread-screenshots + bread-capture: foundation for UI screenshot tooling

New bread-screenshots crate captures a layer-shell surface (by namespace+pid,
to disambiguate from an already-running instance) or the whole focused
output via grim, using bread-utils::hypr/proc. bread-utils::Monitor gains a
scale field and logical_size() so output geometry accounts for HiDPI/
transform, matching breadshot's proven math. bread-utils::hypr gains
find_layer() over hyprctl layers -j.

bread-capture is a small orchestrator that drives an app's --screenshot mode
and collects the resulting PNGs; hardcoded to breadbar's two views for now.

bread-capture/src/main.rs

@@ -0,0 +1,58 @@
+//! Orchestrator for the bread ecosystem's UI screenshot tooling.
+//!
+//! Drives each target app's `--screenshot <view> --output <path>` mode (see
+//! `bread-screenshots` for what that mode does inside the app) and reports
+//! pass/fail per view. Foundation-phase scope: one target (breadbar), a
+//! hardcoded view list, and a flat output directory — no versioned
+//! `screenshots/vX.Y.Z/latest` structure or manifest file yet, since those
+//! only earn their complexity once more apps are wired up.
+
+use anyhow::Result;
+use clap::Parser;
+use std::path::PathBuf;
+use std::time::Duration;
+
+const CAPTURE_TIMEOUT: Duration = Duration::from_secs(10);
+
+/// (view name, output filename)
+const BREADBAR_TARGETS: &[(&str, &str)] = &[
+    ("bar", "breadbar-bar.png"),
+    ("control-panel", "breadbar-control-panel.png"),
+];
+
+#[derive(Parser)]
+struct Cli {
+    /// Path to the breadbar binary (resolved via $PATH if not a path).
+    #[arg(long, default_value = "breadbar")]
+    app_path: String,
+
+    /// Directory to write captured PNGs into.
+    #[arg(long, default_value = "./screenshots")]
+    out_dir: PathBuf,
+}
+
+fn main() -> Result<()> {
+    let cli = Cli::parse();
+
+    let mut failed = false;
+    for (view, filename) in BREADBAR_TARGETS {
+        let out_path = cli.out_dir.join(filename);
+        let out_str = out_path.to_string_lossy();
+        let result = bread_utils::proc::run(
+            &cli.app_path,
+            &["--screenshot", view, "--output", &out_str],
+            CAPTURE_TIMEOUT,
+        );
+        if result.success {
+            println!("ok    breadbar/{view} -> {}", out_path.display());
+        } else {
+            failed = true;
+            println!("FAIL  breadbar/{view}: {}", result.stderr.trim());
+        }
+    }
+
+    if failed {
+        std::process::exit(1);
+    }
+    Ok(())
+}