Adopt bread_utils::screenshot_cli for --screenshot flags

Use the crate for pair validation, settle delay, and canvas defaults
in breadpad and breadman. breadman now depends on bread-utils v0.7.2
for screenshot_cli; existing hand-rolled argv parsing stays.

breadman/Cargo.toml

@@ -13,6 +13,8 @@ path = "src/main.rs"
 breadpad-shared = { path = "../breadpad-shared" }
 # Capture primitives for `--screenshot` mode — see src/screenshot.rs.
 bread-screenshots = { git = "https://git.breadway.dev/Breadway/bread-ecosystem", tag = "v0.7.2" }
+# Shared `--screenshot` pair validation + settle delay (`screenshot_cli`).
+bread-utils = { git = "https://git.breadway.dev/Breadway/bread-ecosystem", tag = "v0.7.2" }
 # `adw` implies `gtk`. Local chip/init shims remain in src/theme_widgets.rs.
 bread-theme = { git = "https://git.breadway.dev/Breadway/bread-ecosystem", tag = "v0.7.2", features = ["adw"] }
 libadwaita = { version = "0.9", features = ["v1_7"] }

breadman/src/main.rs

@@ -20,6 +20,9 @@ mod views;
 // ── Args ─────────────────────────────────────────────────────────────────────
 
 mod args {
+    use bread_utils::screenshot_cli::{validate_pair, DEFAULT_HEIGHT, DEFAULT_WIDTH};
+    use std::path::Path;
+
     #[derive(Debug)]
     pub struct Args {
         pub view: Option<String>,
@@ -32,18 +35,20 @@ mod args {
     }
 
     impl Args {
-        /// `None` for a normal run. Exits the process with an error if
-        /// `--screenshot` was given without `--output`, before any GTK
+        /// `None` for a normal run. Exits the process with an error if the
+        /// `--screenshot` / `--output` pair is incomplete, before any GTK
         /// setup happens.
         pub fn screenshot_request(&self) -> Option<crate::screenshot::ScreenshotRequest> {
-            let view = self.screenshot.clone()?;
-            let Some(output) = self.output.clone() else {
-                eprintln!("breadman: --screenshot requires --output");
+            if let Err(e) = validate_pair(
+                self.screenshot.as_deref(),
+                self.output.as_deref().map(Path::new),
+            ) {
+                eprintln!("breadman: {e}");
                 std::process::exit(1);
-            };
+            }
             Some(crate::screenshot::ScreenshotRequest {
-                view,
-                output: output.into(),
+                view: self.screenshot.clone()?,
+                output: self.output.clone()?.into(),
                 width: self.width,
                 height: self.height,
             })
@@ -57,8 +62,8 @@ mod args {
             upcoming_plain: false,
             screenshot: None,
             output: None,
-            width: 1920,
-            height: 1080,
+            width: DEFAULT_WIDTH,
+            height: DEFAULT_HEIGHT,
         };
         let raw: Vec<String> = std::env::args().skip(1).collect();
         let mut i = 0;

breadman/src/screenshot.rs

@@ -19,6 +19,7 @@
 //! the button/click-handler entirely), with no-op save/delete/error
 //! callbacks since nothing here should actually persist a change.
 
+use bread_utils::screenshot_cli::SETTLE_DELAY;
 use gtk4::prelude::*;
 use libadwaita::prelude::*;
 use std::path::PathBuf;
@@ -26,15 +27,10 @@ use std::rc::Rc;
 use std::sync::Arc;
 use std::time::Duration;
 
-/// Extra settle time after `map` for the first frame to actually paint
-/// before grim runs — `map` fires once the surface exists, not once
-/// anything has been drawn into it.
-const SETTLE_DELAY: Duration = Duration::from_millis(300);
-
 /// Delay before popping the editor popover open — same reasoning as every
 /// other app's PRE_POPUP_DELAY: the parent window's own layout needs a beat
 /// to settle first.
-const PRE_POPUP_DELAY: Duration = Duration::from_millis(300);
+const PRE_POPUP_DELAY: Duration = SETTLE_DELAY;
 
 #[derive(Clone)]
 pub struct ScreenshotRequest {