feat(tui): manage queued drafts and edit or retry questions

[kingsword09]

Add /queue to reorder, delete, or move unsent text drafts into the editor, with /queue pause and /queue resume to control automatic sending. Explicit pauses survive turn transitions, and the picker pauses sending while open. Inputs already accepted by the runtime remain protected from local edits.

Add /edit-message and /retry to select an earlier question and return to it through the existing conversation rewind. Both require an idle conversation and confirmation before removing later turns. Editing restores the question text; retry sends it with the current model. The confirmation explains that original images are not included.

Keep pending images attached to the editor: queueing or restoring unrelated drafts is guarded, and draining an older text draft preserves any image attached afterwards for the next editor submission.

Validation:

• bun run typecheck
• bun run build and bun scripts/check-runtime.ts against locked Desktop 3.14.3
• bun run test:tui
• Queue model/view regressions and five real-terminal scenarios covering reorder, edit, retry, image guards, and preservation followed by delivery of an editor attachment
• Full unit and terminal smoke suites passed during implementation
• git diff --check

[pkg-pr-new]

npx https://pkg.pr.new/zcode-app-cli@7b0fb02

commit: 7b0fb02