feat(lane-outcome): publish duration, tokens and run link per run #885

Split from melodic-software/claude-code-plugins#6974 (and its sibling melodic-software/claude-code-plugins#6973). Both close with this issue as the home for the per-run fields below.

Problem

On 2026-10-16 the owner decided the fields each lane run reports: lane, outcome, duration, turns, models, tokens, estimated cost and run link (recorded on melodic-software/claude-code-plugins#6973 and melodic-software/claude-code-plugins#6974). The lane-outcome record (docs/lane-outcome.md, owned here) publishes lane, outcome, class, credential, turns, maxTurns, models and costUsd (a list-price estimate, #872). Three fields are missing.

Missing fields

• durationMs: the run's duration. Today it shows up only in claude-code-plugins run diagnostics: duration_ms: result.duration_ms at .github/workflows/pr-run-activity-read.yml:1609 and .github/workflows/pr-run-activity-write.yml:1531.
• tokens: input, output and cache tokens per run, from the result message's usage.
• run link: the run URL, or the run id and attempt to build it, in the record itself. The annotation sits on its run, but a reader holding only the record cannot get back to the run.

Still private and out of scope: the role-to-account mapping, usage percentages, and transcripts.

Done when

• schemas/lane-outcome.v1.schema.json (or a v2) defines durationMs, a tokens object and a run reference, and docs/lane-outcome.md documents them.
• report-lane-outcome emits all three for every lane whose run has them.
• A record carrying all fields stays within the 1,024-character limit, or the doc says which field is dropped first.
• Existing readers of v1 records (claude-code-account-rotation's limit-stop check) still parse them.