feat: Add context-aware functions

[jkroepke]

In rare cases, where xdg-open hangs, kill it if context is canceled.

[Copilot]

Pull request overview

This PR adds context-aware variants of the public browser-opening helpers so that callers can cancel the underlying OS command (notably to stop hung xdg-open processes).

Changes:

• Introduce OpenFileContext, OpenReaderContext, and OpenURLContext, and re-route existing APIs through context.Background().
• Plumb context.Context through openBrowser and runCmd via exec.CommandContext.
• Update examples to use the new *Context APIs.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
example_test.go	Updates examples to call the new context-aware APIs.
browser.go	Adds exported *Context functions and updates runCmd to use exec.CommandContext.
browser_linux.go	Threads context through Linux browser provider execution.
browser_freebsd.go	Threads context into xdg-open invocation.
browser_openbsd.go	Threads context into xdg-open invocation.
browser_netbsd.go	Threads context into xdg-open invocation.
browser_darwin.go	Threads context into open invocation on macOS.
browser_windows.go	Updates openBrowser signature to accept context (unused on Windows).
browser_unsupported.go	Updates openBrowser signature to accept context and adds //go:build line.

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[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (1)

browser.go:49

• OpenReaderContext currently only uses ctx when launching the browser (OpenFileContext), but it will still create a temp file and fully io.Copy() the reader even if ctx is already canceled. This makes the new context-aware API not actually cancellable for potentially expensive reads, and it can also leave behind temp files on cancellation/open errors. Consider failing fast on ctx.Err() and cleaning up the temp file on any error (including ctx cancellation and OpenFileContext failure).

func OpenReaderContext(ctx context.Context, r io.Reader) error {
f, err := os.CreateTemp("", "browser.*.html")
if err != nil {
return fmt.Errorf("browser: could not create temporary file: %w", err)
}