chore(infra): retire alpha-engine-friday-shell-run cron rule (L4055)

[cipher813]

What

Removes the superseded fixed-time Friday cron rule alpha-engine-friday-shell-run from CloudFormation. Closes ROADMAP gate L4055.

Why now — gate cleared (verified live)

The cron was replaced by the event-driven alpha-engine-eod-success-friday-shell-trigger Lambda (#282, merged 2026-05-21), which fires the Saturday SF in shell_run mode on the Friday EOD-SF SUCCEEDED transition (trading_day-bound, not wall-clock). The cron ran DISABLED from the 5/21 cutover. Gate L4055 required the event-driven path to confirm across two Fridays — done:

Fire	Date	Trigger	Shell-run SF
1st	2026-05-22	✅ fired correctly	FAILED (preflight/transient, same week as the known SF-blocker workstream)
2nd	2026-05-29	✅ fired correctly	SUCCEEDED (28 min, clean)

Verified live before deletion: cron State=DISABLED; trigger Lambda Active; both friday-shell-* Saturday-SF executions present.

Changes

• CFN alpha-engine-orchestration.yaml — remove the FridayShellRunTrigger AWS::Events::Rule (deploying the stack removes the rule + its single target). No other resource references the logical ID.
• step_function.json — update the shell_run-gate comment to point at the event-driven Lambda. The gate itself is unchanged (strict superset; the Lambda still supplies {"shell_run": true}).
• index.py (trigger Lambda) — restore pipeline_role: "shell-run" in the shell-run input. Audit finding: the Lambda dropped the tag the cron carried, so since the 5/21 cutover Friday shell-runs ran without the page-25 role-filter surface tag. Fixed here so the event-driven path is a faithful replacement, not a surface regression.
• deploy.sh — comment updated (cron retired, not just disabled).
• Tests — TestFridayEventBridgeRule (4 rule-presence tests) → one inverted regression guard asserting the rule stays removed; _TRIGGER_SUCCESSORS map + the Friday-Input test updated for the removed block; the trigger Lambda test now asserts pipeline_role="shell-run".

Verification

• aws cloudformation validate-template OK; step_function.json valid JSON.
• Full suite: 1683 passed, 1 skipped. Trigger Lambda suite: 13 passed.

Deploy (operator, on merge)

1. aws cloudformation deploy the orchestration stack → removes the cron rule + target.
2. Redeploy the trigger Lambda (infrastructure/lambdas/eod-success-friday-shell-trigger/deploy.sh) so the pipeline_role tag takes effect on the next Friday shell-run.

🤖 Generated with Claude Code