feat: in-app update notice — checks GitHub releases on startup

Adds a one-shot update check that runs on app boot and pops up a small
"Update Available" window when the GitHub releases API reports a newer
tag than this build's `CARGO_PKG_VERSION`.

- `src/update_check.rs` — async wrapper around a blocking `ureq` GET to
  `api.github.com/repos/HakanSeven12/H7CAD/releases/latest`, returns
  `Some(version)` when a newer release exists, `None` otherwise (silent
  on network / parse failure so a missing connection never blocks
  launch).
- `H7CAD::boot` chains a `Task::perform` next to the main-window open
  so the check runs in parallel with first-paint.
- New window plumbed like the other floating panels (page setup, about,
  etc.): `update_notice_window`/`update_notice_version` state, title
  entry, `OsWindowClosed` cleanup, and a `ui::update_notice::view_window`
  modal that shows installed vs. latest version plus "Later" /
  "Open Release Page" buttons. Open routes through `open::that` to the
  releases URL and dismisses the modal.

Dependency: adds `ureq = { version = "2", default-features = false,
features = ["tls"] }` — the smallest blocking HTTP client + TLS combo
that doesn't drag in an async runtime.

Co-Authored-By: Claude Opus 4.7 <[email protected]>

src/ui/mod.rs

@@ -4,6 +4,7 @@ pub const ROW_H: f32 = 26.0;
 
 pub mod about;
 pub mod app_menu;
+pub mod update_notice;
 pub mod command_line;
 pub mod dimstyle;
 pub mod layers;

src/ui/update_notice.rs

@@ -0,0 +1,167 @@
+use crate::app::Message;
+use iced::widget::{button, column, container, row, text, Space};
+use iced::{Background, Border, Color, Element, Fill, Theme};
+
+const BG: Color = Color {
+    r: 0.15,
+    g: 0.15,
+    b: 0.15,
+    a: 1.0,
+};
+const PANEL: Color = Color {
+    r: 0.12,
+    g: 0.12,
+    b: 0.12,
+    a: 1.0,
+};
+const BORDER: Color = Color {
+    r: 0.30,
+    g: 0.30,
+    b: 0.30,
+    a: 1.0,
+};
+const DIM: Color = Color {
+    r: 0.55,
+    g: 0.55,
+    b: 0.55,
+    a: 1.0,
+};
+const ACCENT: Color = Color {
+    r: 0.25,
+    g: 0.50,
+    b: 0.85,
+    a: 1.0,
+};
+const WHITE: Color = Color {
+    r: 0.92,
+    g: 0.92,
+    b: 0.92,
+    a: 1.0,
+};
+
+fn info_row<'a>(label: &'static str, value: String) -> Element<'a, Message> {
+    row![
+        text(label).size(11).color(DIM).width(100),
+        text(value).size(11).color(WHITE),
+    ]
+    .spacing(8)
+    .align_y(iced::Center)
+    .padding([3, 0])
+    .into()
+}
+
+pub fn view_window<'a>(latest: &'a str) -> Element<'a, Message> {
+    let header = container(
+        column![
+            text("New Release Available").size(20).color(ACCENT),
+            text("A newer H7CAD version is published on GitHub.")
+                .size(11)
+                .color(DIM),
+        ]
+        .spacing(4)
+        .align_x(iced::Center),
+    )
+    .width(Fill)
+    .padding(iced::Padding {
+        top: 16.0,
+        right: 0.0,
+        bottom: 14.0,
+        left: 0.0,
+    })
+    .align_x(iced::Center);
+
+    let info_block = container(
+        column![
+            info_row("Installed", format!("v{}", env!("CARGO_PKG_VERSION"))),
+            info_row("Latest", format!("v{}", latest)),
+        ]
+        .spacing(2)
+        .padding([12, 16]),
+    )
+    .width(Fill)
+    .style(|_: &Theme| container::Style {
+        background: Some(Background::Color(PANEL)),
+        border: Border {
+            color: BORDER,
+            width: 1.0,
+            radius: 4.0.into(),
+        },
+        ..Default::default()
+    });
+
+    let later_btn = button(text("Later").size(11))
+        .on_press(Message::UpdateNoticeClose)
+        .style(|_: &Theme, st| button::Style {
+            background: Some(Background::Color(match st {
+                button::Status::Hovered | button::Status::Pressed => Color {
+                    r: 0.22,
+                    g: 0.22,
+                    b: 0.22,
+                    a: 1.0,
+                },
+                _ => Color {
+                    r: 0.18,
+                    g: 0.18,
+                    b: 0.18,
+                    a: 1.0,
+                },
+            })),
+            text_color: WHITE,
+            border: Border {
+                color: BORDER,
+                width: 1.0,
+                radius: 4.0.into(),
+            },
+            ..Default::default()
+        })
+        .padding([6, 16]);
+
+    let open_btn = button(text("Open Release Page").size(11))
+        .on_press(Message::UpdateNoticeOpenRelease)
+        .style(|_: &Theme, st| button::Style {
+            background: Some(Background::Color(match st {
+                button::Status::Hovered | button::Status::Pressed => Color {
+                    r: 0.20,
+                    g: 0.42,
+                    b: 0.72,
+                    a: 1.0,
+                },
+                _ => ACCENT,
+            })),
+            text_color: WHITE,
+            border: Border {
+                radius: 4.0.into(),
+                ..Default::default()
+            },
+            ..Default::default()
+        })
+        .padding([6, 16]);
+
+    let footer = row![Space::new().width(Fill), later_btn, open_btn]
+        .spacing(8)
+        .align_y(iced::Center)
+        .padding(iced::Padding {
+            top: 14.0,
+            right: 0.0,
+            bottom: 0.0,
+            left: 0.0,
+        });
+
+    container(
+        column![header, info_block, footer]
+            .spacing(0)
+            .padding(iced::Padding {
+                top: 0.0,
+                right: 20.0,
+                bottom: 20.0,
+                left: 20.0,
+            }),
+    )
+    .style(|_: &Theme| container::Style {
+        background: Some(Background::Color(BG)),
+        ..Default::default()
+    })
+    .width(Fill)
+    .height(Fill)
+    .into()
+}