feat(nesdoctor): put the line on the clipboard, and ask for the JSON properly

Two problems with how the run ended, both about presentation rather than data.

The summary line was set in the same dim grey as the paragraphs around it and
had to be found, then hand-selected out of a terminal. It is now a reverse-video
block under a "Copy this" rule, and it is copied to the clipboard automatically
via wl-copy, xclip, xsel, pbcopy or clip -- whichever the desktop has. Where
none is present we say so and mention the package, so it works by itself next
time. Selecting a long line out of a terminal was the last step before we learn
anything, so it should not be work.

And the JSON was described defensively -- "goes nowhere unless you send it" --
which reads as though we expect to be distrusted, and inviting the doubt is a
good way to create it. The file is genuinely the more valuable artefact: it
carries every check with its reason, the full latency series, and installed
titles with sizes and launch times. So it now says that, says what it is for,
and asks for it: read through it, send it along if nothing in there bothers
you, and the line is already plenty if not.

The consent model does not change -- no server exists, nothing is uploaded, and
Steam still needs an explicit yes asked last. What changes is that we stop
apologising for asking.

apps/nesdoctor/README.md

@@ -21,8 +21,16 @@ rather than a promise about our intentions: there is nothing to switch on later.
 
 The shareable line carries **no hostname, no IP, no username, no game titles and
 no file paths** — a size band rather than a size, and an hour histogram rather
-than timestamps. The long version does include titles and paths, and it stays in
-`nesdoctor.json` on your disk.
+than timestamps. It is put on your clipboard at the end so pasting it is one
+keystroke.
+
+The long version lands in `nesdoctor.json`: every check with its reason, the
+full latency series, and your installed titles with sizes and launch times if
+you said yes to Steam. **That file is considerably more useful to us than the
+line** — it is what lets us size a game library and see which requirement
+actually stops people — so do have a read through it and send it along if
+nothing in there bothers you. Plain JSON, entirely optional, and the one-line
+version is already plenty.
 
 Reading your Steam library needs an explicit yes, and the question is asked last,
 after you have seen what this program does.

apps/nesdoctor/src/main.rs

@@ -206,27 +206,62 @@ fn main() {
         return;
     }
 
+    let clip = report::to_clipboard(&line);
+
     println!();
-    println!("\x1b[1mThe line to share, if you want to\x1b[0m");
-    println!(
-        "\x1b[2m  No hostname, no IP, no username, no game titles, no paths. A size band\x1b[0m"
-    );
-    println!("\x1b[2m  rather than a size, and hours rather than dates. Read it yourself:\x1b[0m");
+    println!("\x1b[1m─── Copy this ───────────────────────────────────────────────────\x1b[0m");
     println!();
-    println!("  {line}");
+    println!("\x1b[1;97;44m {line} \x1b[0m");
     println!();
-    if wrote {
-        println!(
-            "\x1b[2mThe long version — which does include titles and paths — is in {} and\x1b[0m",
-            args.json.display()
-        );
-        println!("\x1b[2mgoes nowhere unless you send it.\x1b[0m");
+    match clip {
+        Some(tool) => println!(
+            "\x1b[32m  ✓ Already on your clipboard\x1b[0m \x1b[2m(via {tool}) — just paste it.\x1b[0m"
+        ),
+        None => println!(
+            "\x1b[2m  Select the line above to copy it. (Install wl-clipboard or xclip and\x1b[0m\n\x1b[2m  this happens by itself next time.)\x1b[0m"
+        ),
     }
     println!();
     println!(
-        "\x1b[2mIf you are willing: paste that line into the thread you got this from.\x1b[0m"
+        "\x1b[2m  Every field is above: no hostname, no IP, no username, no game titles,\x1b[0m"
     );
-    println!("\x1b[2mIt is the only way we learn what the machines on the other end are.\x1b[0m");
+    println!("\x1b[2m  no paths. A size band rather than a size, hours rather than dates.\x1b[0m");
+    println!();
+    println!("\x1b[1m  → Paste it into the thread you got this from.\x1b[0m");
+    println!(
+        "\x1b[2m    It is the only way we find out what the machines on the other end are,\x1b[0m"
+    );
+    println!("\x1b[2m    and right now we genuinely have no idea.\x1b[0m");
+
+    if wrote {
+        println!();
+        println!("\x1b[1mAnd if you feel like being properly helpful\x1b[0m");
+        println!(
+            "\x1b[2m  {} has the long version: every check with its reason, the full\x1b[0m",
+            args.json.display()
+        );
+        println!(
+            "\x1b[2m  latency series, and — if you said yes to Steam — your installed titles\x1b[0m"
+        );
+        println!("\x1b[2m  with their sizes and launch times.\x1b[0m");
+        println!();
+        println!(
+            "\x1b[2m  That file is more useful to us than the line by a long way: it is what\x1b[0m"
+        );
+        println!(
+            "\x1b[2m  lets us size a game library properly and see which requirement actually\x1b[0m"
+        );
+        println!(
+            "\x1b[2m  stops people. Have a look through it — it is plain JSON — and send it\x1b[0m"
+        );
+        println!(
+            "\x1b[2m  along if nothing in there bothers you. Entirely optional, and the\x1b[0m"
+        );
+        println!("\x1b[2m  line above is already plenty.\x1b[0m");
+    }
+    println!();
+    println!("\x1b[2mThanks. Genuinely — this is the part we cannot do on our own.\x1b[0m");
+    println!();
 }
 
 fn banner() {

apps/nesdoctor/src/report.rs

@@ -310,3 +310,44 @@ fn wrap(s: &str, width: usize) -> Vec<String> {
     out.retain(|l| !l.is_empty());
     out
 }
+
+/// Put the summary line on the clipboard, and say which tool did it.
+///
+/// Selecting a long line out of a terminal is fiddly and it is the last step
+/// before we learn anything, so it should not be work. Every one of these ships
+/// with the desktop it belongs to; where none is present we simply say so and
+/// the line is still on screen.
+pub fn to_clipboard(line: &str) -> Option<&'static str> {
+    use std::io::Write;
+    use std::process::{Command, Stdio};
+
+    const TOOLS: [(&str, &[&str]); 5] = [
+        ("wl-copy", &[]),                        // Wayland
+        ("xclip", &["-selection", "clipboard"]), // X11
+        ("xsel", &["--clipboard", "--input"]),   // X11, the other one
+        ("pbcopy", &[]),                         // macOS
+        ("clip", &[]),                           // Windows
+    ];
+
+    for (tool, args) in TOOLS {
+        let Ok(mut child) = Command::new(tool)
+            .args(args)
+            .stdin(Stdio::piped())
+            .stdout(Stdio::null())
+            .stderr(Stdio::null())
+            .spawn()
+        else {
+            continue;
+        };
+        let wrote = child
+            .stdin
+            .as_mut()
+            .is_some_and(|s| s.write_all(line.as_bytes()).is_ok());
+        // Wait either way, so a failed tool is not left running.
+        let ok = child.wait().map(|s| s.success()).unwrap_or(false);
+        if wrote && ok {
+            return Some(tool);
+        }
+    }
+    None
+}