feat(ui): OCS Web button, prefilled feedback, drop Start About button

- Add an "OCS Web" button (bright ribbon-blue, desktop only) to the Start
  page that opens the web build at hakanseven12.github.io/OpenCADStudio.
- Send Feedback now opens the GitHub issue with the body pre-filled:
  app version + platform (OS/arch on desktop, browser user-agent on web),
  via sys::platform_info + sys::percent_encode.
- Remove the redundant About button from the Start page (ABOUT command /
  menu still opens it).

Native + web build; 75 tests pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Cargo.toml

@@ -87,6 +87,7 @@ js-sys = "0.3"
 # window.open (external URLs) + Blob/anchor file downloads (Save).
 web-sys = { version = "0.3", features = [
     "Window",
+    "Navigator",
     "Document",
     "Element",
     "HtmlAnchorElement",

src/app/commands.rs

@@ -36,7 +36,7 @@ impl OpenCADStudio {
             && !matches!(
                 cmd,
                 "NEW" | "OPEN" | "EXIT" | "QUIT" | "REPORT" | "CHANGELOG" | "ABOUT"
-                    | "PLUGINS" | "PLUGINMANAGER" | "DONATE"
+                    | "PLUGINS" | "PLUGINMANAGER" | "DONATE" | "WEBVERSION"
             )
         {
             self.command_line
@@ -2505,6 +2505,11 @@ impl OpenCADStudio {
                 self.command_line.push_info("Opening Patreon page...");
             }
 
+            "WEBVERSION" => {
+                crate::sys::open_url("https://hakanseven12.github.io/OpenCADStudio/");
+                self.command_line.push_info("Opening OCS Web...");
+            }
+
             // ── DWGPROPS — print round-trip-only HeaderVariables ─────────
             // No UI dialog for these yet; the command surfaces them so
             // users can confirm the values that the parser populated and
@@ -2681,7 +2686,19 @@ impl OpenCADStudio {
             }
 
             "REPORT" => {
-                crate::sys::open_url("https://github.com/HakanSeven12/OpenCADStudio/issues/new");
+                // Pre-fill the GitHub issue body with version + platform so
+                // reports arrive with the basics already filled in.
+                let body = format!(
+                    "<!-- Describe the issue and the steps to reproduce it. -->\n\n\n\
+                     ---\n- Open CAD Studio: v{}\n- Platform: {}\n",
+                    env!("CARGO_PKG_VERSION"),
+                    crate::sys::platform_info(),
+                );
+                let url = format!(
+                    "https://github.com/HakanSeven12/OpenCADStudio/issues/new?body={}",
+                    crate::sys::percent_encode(&body)
+                );
+                crate::sys::open_url(&url);
                 self.command_line.push_info("Opening feedback page...");
             }
 

src/app/view.rs

@@ -3779,7 +3779,7 @@ pub(super) fn start_page_view<'a>() -> Element<'a, Message> {
     .spacing(12)
     .align_y(iced::Center);
 
-    let secondary_row = row![
+    let mut secondary_row = row![
         outline_btn(
             "Send Feedback",
             Message::RibbonToolClick {
@@ -3795,10 +3795,50 @@ pub(super) fn start_page_view<'a>() -> Element<'a, Message> {
             },
         ),
         outline_btn("Plugins", Message::PluginManagerOpen),
-        outline_btn("About", Message::AboutOpen),
-    ]
-    .spacing(12)
-    .align_y(iced::Center);
+    ];
+    // The web build is already in the browser, so only the desktop offers a
+    // link to the web version.
+    #[cfg(not(target_arch = "wasm32"))]
+    {
+        // Bright ribbon blue (matches the active-tool accent), filled.
+        secondary_row = secondary_row.push(
+            button(text("OCS Web").size(14).color(Color::WHITE))
+                .on_press(Message::RibbonToolClick {
+                    tool_id: "WEBVERSION".to_string(),
+                    event: crate::modules::ModuleEvent::Command("WEBVERSION".to_string()),
+                })
+                .padding([10, 22])
+                .style(|_: &Theme, status| button::Style {
+                    background: Some(Background::Color(match status {
+                        button::Status::Hovered => Color {
+                            r: 0.15,
+                            g: 0.45,
+                            b: 0.78,
+                            a: 1.0,
+                        },
+                        _ => Color {
+                            r: 0.20,
+                            g: 0.55,
+                            b: 0.90,
+                            a: 1.0,
+                        },
+                    })),
+                    text_color: Color::WHITE,
+                    border: Border {
+                        color: Color {
+                            r: 0.20,
+                            g: 0.55,
+                            b: 0.90,
+                            a: 1.0,
+                        },
+                        width: 1.0,
+                        radius: 6.0.into(),
+                    },
+                    ..Default::default()
+                }),
+        );
+    }
+    let secondary_row = secondary_row.spacing(12).align_y(iced::Center);
 
     let card_section = |heading: &'static str, sub: &'static str, body: &'static str| {
         container(

src/sys.rs

@@ -59,3 +59,33 @@ pub fn download_bytes(name: &str, bytes: &[u8]) {
     }
     let _ = web_sys::Url::revoke_object_url(&url);
 }
+
+/// Short platform string for bug reports: OS + architecture on the desktop,
+/// the browser user-agent on the web.
+#[cfg(not(target_arch = "wasm32"))]
+pub fn platform_info() -> String {
+    format!("{} {}", std::env::consts::OS, std::env::consts::ARCH)
+}
+
+#[cfg(target_arch = "wasm32")]
+pub fn platform_info() -> String {
+    web_sys::window()
+        .and_then(|w| w.navigator().user_agent().ok())
+        .map(|ua| format!("Web — {ua}"))
+        .unwrap_or_else(|| "Web (wasm)".to_string())
+}
+
+/// Percent-encode `s` for use in a URL query value (e.g. a GitHub issue
+/// `?body=`). Encodes everything outside the unreserved set.
+pub fn percent_encode(s: &str) -> String {
+    let mut out = String::with_capacity(s.len());
+    for &b in s.as_bytes() {
+        match b {
+            b'A'..=b'Z' | b'a'..=b'z' | b'0'..=b'9' | b'-' | b'_' | b'.' | b'~' => {
+                out.push(b as char)
+            }
+            _ => out.push_str(&format!("%{b:02X}")),
+        }
+    }
+    out
+}