Allow refine from ready, returning through triage

[MJohnson459]

Refine now fires from ready as well as proposed, so a task triaged before refine existed can have its body agent-rewritten instead of hand-edited through voro set --body-file.

What changed

• voro-core/src/transition.rs: the transition arm widens to (Proposed | Ready, Action::Refine(_)) => Refining, for both intensities (the note-driven and interactive flavours are one action carrying different notes). legal_actions still withholds refine — it collects verdicts, and refine is not one — so only the apply match and the test matrix moved.
• The conclude transition is untouched: refining → proposed, always. A round keeps no memory of its origin, so a task refined out of ready deliberately returns through triage — the ready verdict was passed on a body that no longer exists, so the rewrite earns a fresh verdict. No refining → ready arm, no origin state.
• parked stays excluded.
• voro/src/dispatch.rs: guard_refinable — the early refusal both flavours share — accepts Ready; the message becomes "only a proposed or ready task can be refined".
• voro/src/app.rs: is_proposed becomes is_refinable (proposed or ready), and refine_selected's shared guard follows, refusing with "task is {state} — refine works on a proposal or a ready task".
• voro/src/ui.rs: the r/R refine key-line slot is advertised on a selected ready row on both the cockpit and the task browser; the ? key map's uppercase gloss rewords to "refine a brief". The cockpit line stays within its ten slots on a ready row (⏎, d/D, r/R, s, !, n/N, e, ?, tab, q).
• voro/src/cli.rs: voro triage <id> refine is unchanged apart from the widened guard — no new verb — and the --help transitions entry and the handler doc say so.
• docs/DESIGN.md: §6's state table (ready gains the refine transition; the refining row's "entered from" and "leaves by" prose), a new paragraph of rationale after the refine-is-a-state argument, and the §6 sentences that said refine is refused on anything but a proposal.

Nothing else needed code changes, which was verified rather than assumed: the ↻ refined / ⚠ refine failed markers, the session row, reconcile of dead refine rounds, and scoring all hang off the refining state and the proposed landing, not the origin.

Tests

voro-core gains a transition::tests::refine module: a ready task refines in either flavour and opens its session row in the same write; every round concludes to proposed whatever it started from, across all three RefineOutcomes; refine is refused from every other state including parked, running, review, needs-input, waiting, stalled and the closed pair; and a refining task drops out of candidates()/focus(), which is the dispatch race closed by construction. Two existing "refused from the wrong state" tests move their fixture from ready to parked, and voro's dispatch tests gain a ready-task refine round-trip. app.rs gains a positive r-on-a-ready-row test beside the reworked refusal test.

Verified

cargo test --workspace (619 tests) and cargo clippy --workspace --all-targets -- -D warnings pass; cargo fmt --all --check clean.

Driven end-to-end in the TUI against a scratch database with a stub agent: on a selected ready row the key line advertises r/R refine; r opens the "Refine note — what needs fixing" prompt; submitting it moves the task off the queue onto the running strip as ⟳ refining (header refining 1 ready 1); when the stub's voro set --body lands, the task returns as a proposal marked ↻ refined — ↻ 1 refined on the folded digest, ↻ refined on the row — with the rewritten body and a refined event carrying the note. voro triage 2 refine --note "…" accepts a ready id from the CLI. While a round is in flight voro next reports "no ready tasks" and voro dispatch refuses with "only ready or stalled tasks can be dispatched; task 3 is refining"; on a parked task refine refuses with "only a proposed or ready task can be refined".

Branch refine-from-ready, one commit, not pushed.