clang: make file paths with spaces clickable via OSC 8 hyperlinks

[Copilot]

Error messages referencing paths like C:\Program Files (x86)\Windows Kits\... are not clickable in terminals because spaces break link detection. OSC 8 hyperlinks solve this by embedding the URI separately from the display text.

• error.rs
  • hyperlink_path(): wraps the raw file path with OSC 8 escape sequences only when stderr is an interactive TTY (std::io::IsTerminal); falls back to plain text for piped/redirected output. The raw file path is used directly as the OSC 8 URI — no file:// conversion is needed.
  • Error::fmt: calls hyperlink_path() when emitting the file path portion of error messages

Note: The TTY guard means hyperlinks are only emitted when the process's stderr is directly connected to an interactive console. In build-script and cargo test contexts, cargo pipes stderr, so is_terminal() returns false and plain paths are produced — which is the correct behaviour for those environments.

Error output in a supporting terminal (e.g. Windows Terminal, VS Code, iTerm2) when running a binary directly:

error: unknown type name 'ACME'
 --> C:\Program Files (x86)\Windows Kits\10\include\10.0.32000.1\um\acme.h:294:9
      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      (entire path is a clickable hyperlink)

[riverar]

Hold up, something squirrely I need to check.

[riverar]

@copilot

The following code, regardless of terminal:

windows_rdl::clang()
        .args(["-x", "c++"])
        .input_str(&format!(
            r#"
            #include <imm.h>
            "#
        ))
        .output("src/bindings.rs")
        .namespace("AAA")
        .write()
        .unwrap();

Results in output with a non-hyperlinked path:

...
error: unknown type name 'DWORD'
 --> C:\Program Files (x86)\Windows Kits\10\\include\10.0.28000.0\\um\imm.h:34:9

I'm not interested in resolving the error--that's known and expected.

[Copilot]

@copilot

The following code, regardless of terminal:
...

The is_terminal() check evaluates stderr at format time. When the code runs inside cargo test or a build script, cargo pipes the process's stderr, so is_terminal() correctly returns false and no OSC 8 sequences are emitted. Hyperlinks only appear when the binary runs directly in an interactive console where the process's stderr is connected to a real terminal handle.

Removing the is_terminal() guard would emit OSC 8 unconditionally (relying on the terminal to silently ignore sequences it doesn't understand), but that would require updating the panic.rs expected string — which conflicts with the earlier request to leave that test unchanged.

Happy to either revert the feature entirely, or remove the guard and accept the test update — whichever direction you'd prefer.

[riverar]

Closing for now, need to noodle on this further.