ledger: lanes that halt on an external decision record 'completed' — need a 'blocked' terminal state with reason

[agents-squads]

Observed (2026-07-17)

A lane correctly halted mid-plan on an external gate (a required vendor component turned out to be behind a license key; standing directive forbids hand-rolling a copy). It ended its turn cleanly — and the ledger recorded a plain completed with zero artifacts, indistinguishable from the zero-deliverable false-success class (#1130/#1149) and invisible on the board as anything needing attention.

Fix

• Terminal classification: run ends with no pushed branch/PR AND the final message declares a blocker → status=blocked + blocked_reason (from the result text), not completed.
• blocked rows surface in squads status/board as needs-attention (amber), and in the kanban's stall/triage lane (squads-app#159 — this is exactly its 'catch up with tasks that don't move' requirement).
• Harness nudge: a lane declaring a blocker should also comment it on the issue before ending (tonight the orchestrator had to transplant the finding from the stream log to the issue by hand).

Builds on #1149's classifier seam. Public-repo hygiene: no internal vendor/pricing details in this issue.

[agents-squads]

Scoping note (loop close, 2026-07-19): this is the one remaining tractable-bug carry-over, deliberately NOT rushed — a new terminal status ripples through three repos' vocabulary (CLI ledger + board, api status filters incl. the runs LIVE_STATUSES/terminal sets and the #259 feed guard, app kanban lanes). Plan: (1) classifier slice on #1149's seam — terminal report with no pushed branch/PR AND a blocker-declaring final message → status=blocked + blocked_reason (first 200 chars); (2) ledger + squads status/board render blocked as amber needs-attention; (3) api: add 'blocked' to the terminal vocab (NOT in LIVE_STATUSES; excluded from the #259 heartbeat-noise predicate since it has a reason payload); (4) app kanban: blocked rows land in the stall/triage lane with the reason on the card; (5) harness nudge: blocker declared → comment it on the worked issue before ending. One PR per repo, cli first (it owns the classification).