feat(evals): stamp trial series identities and fit panels to the live registry

- scripts/eval-trial-series.ts stamps series_identity (eval-flake-rank's
  caseSeriesIdentities) on a report's trial-outcomes JSONL as its own step,
  keeping the history tool out of the paid runner's closure;
  TrialOutcomeRecord gains the optional series_identity field.
- Slice-count plans let a registered trial spill into an ordinary lane when
  its siblings hold every long lane, so panels never share a runner.
- Re-audited test-selection.ts (Stream B added the E2E_KINDS/BEHAVIOR_WHY
  map-diff; no new module loading) and repinned its hash.
- Detach and release floors now count trial shards (66 periodic trials in
  22 panels): periodic floor 33,821s, still under eval:bg:periodic's 67,380s.
- Coordination fixtures supply the executor's trial records.

test/helpers/eval-store.ts

@@ -402,6 +402,8 @@ export interface TrialOutcomeRecord {
   sha?: string;
   lane?: string;
   recorded_at?: string;
+  /** History series key: a hash of the case's own touchfiles (GLOBAL_TOUCHFILES excluded), stamped by the report job. */
+  series_identity?: string;
 }
 
 /** First line of free text, stripped of @-mentions and control characters, capped. */
@@ -434,6 +436,7 @@ function trialRecordProblems(r: any): string[] {
   if (r.execution !== 'executed' && r.execution !== 'reused') problems.push('execution invalid');
   if (!['shard', 'junit', 'backfill'].includes(r.source)) problems.push('source invalid');
   if (r.error !== undefined && (typeof r.error !== 'string' || r.error.length > TRIAL_ERROR_MAX)) problems.push('error invalid');
+  if (r.series_identity !== undefined && (typeof r.series_identity !== 'string' || !/^[\w.-]{1,64}$/.test(r.series_identity))) problems.push('series_identity invalid');
   return problems;
 }