feat(setup): copy wizard code blocks with c - #771

Requirements

• I have added test coverage for new or changed functionality
• I have followed the repository's pull request submission guidelines
• I have validated my changes against all supported platform versions

Related issues

REL-15243, under the CLI Onboarding Wizard A/B epic (REL-15183).

Stacked on #753, which introduces cmd/setup.

Describe the solution you've provided

• Add a c keybinding at the wizard's final screen that copies the raw init snippet — or the install command, when there is no snippet — to the system clipboard via OSC 52
• Label the action next to the code block and confirm it once copied, so the key is discoverable and its effect visible
• Inject the clipboard writer on wizardModel so tests assert the emitted sequence instead of writing to the terminal

The code block is drawn with a left gutter bar, so selecting it with the mouse copies the gutter characters and the padding lipgloss squares the block off with, and pasting that fails on every line. The wizard also runs in the alternate screen, so the snippet is not in scrollback once it exits — the copy has to happen while the TUI is live, which is exactly when the gutter is in the way.

Known limitation: OSC 52 support cannot be detected, and some terminals (including Apple Terminal) do not implement it. There, c reports success while the clipboard is untouched.

Describe alternatives you've considered

• Removing the gutter bar so mouse selection copies cleanly. Rejected: it gives up the visual distinction between copy-me code and prose, and still copies the leading padding.
• Printing the snippet unstyled after the wizard exits, so it lands in scrollback. Complementary rather than alternative, and it also covers the terminals that ignore OSC 52 — worth doing, but a separate change.

Additional context

github.com/charmbracelet/x/ansi moves from an indirect to a direct dependency for SetSystemClipboard. It was already in the module graph via lipgloss; no new module is added.

Testing approaches

• Six new tests in cmd/setup/copy_test.go: the copied payload is byte-for-byte the raw snippet (asserted by decoding the OSC 52 base64, and by asserting the rendered view does contain the gutter bar the copy does not), snippet preferred over install command when both show, fallback to the command, no write on screens with nothing to copy, hint switches to confirmation, and c still reaches the list filter while filtering.
• go build ./..., go vet, gofmt, and go test ./... clean; 51 subtests in cmd/setup; golangci-lint passed via pre-commit.
• Not verified against a real terminal: emitting OSC 52 requires a tty that interprets it, which this environment does not provide. Worth a manual check in iTerm2 or kitty before merge.