The terminal lists a repository's labels, makes one and deletes one with a confirm, as MCP `repo_labels` does #7255

For: a writer who sorts issues from the terminal and finds the label they need missing. The issue screen can pick labels but nothing in the terminal makes or removes them.

listLabels (src/core/issues.ts), createLabel and deleteLabel (src/actions/repos.ts) are reached from the repository's labels page and MCP repo_labels. No terminal screen calls the last two.

Done:

• [ ] A new src/tui/screens/labels.ts, opened from a repository's commands as "Labels". It lists each label with its colour chip (labelChip) and how many open issues carry it.
• [ ] n asks for a name and six hex digits and makes it through createLabel; a taken or malformed one says the LABEL_WORDS words, and nothing is made.
• [ ] d deletes the selected label after a confirm that names how many issues lose it, through deleteLabel.
• [ ] Only someone the action admits is offered n and d; a reader sees the list alone.
• [ ] A new test/tui-labels.test.ts: list, make, refuse a bad colour, delete after a confirm; a reader is offered neither key.

Files: src/tui/screens/labels.ts, the repository's command list, one test. Risk: low; reuse the actions.

Parked by the crew: the check stayed red through 2 automatic tries (pull #7280 closed). Planner: split this smaller, or rewrite what done looks like; a person can also say what to try.

Parked by the crew: the check stayed red through 2 automatic tries (pull #7458 closed).

Parked twice since a person last spoke here, so it is the planner's now. Every reason:

1. the check stayed red through 2 automatic tries (pull #7280 closed)
2. the check stayed red through 2 automatic tries (pull #7458 closed)

The planner splits it, replaces it with a fresh issue, or defers it; a person can also say what to try. Nothing starts here until then, and the board lists it.

Split by the planner. Both tries (pulls #7280 and #7458) grew past the ask: they added sealed-aware use counts in src/core/issues.ts and touched many files, and the check stayed red. The work is now three smaller pieces. #7841 is a read-only list with no new core query. #7842 adds n to make a label, and #7843 adds d to delete one after a confirm. Both wait on #7841.