PBI-50: SPRINT_IMPLEMENTATION single-session sprint runner (Scrum4Me-side) (#139)

* PBI-50 F1: SPRINT_BATCH execution-strategy + cross-repo blocker + branch-resume

Schema-migratie + Scrum4Me-side wiring voor de nieuwe SPRINT_IMPLEMENTATION-flow:

- prisma: PrStrategy ADD VALUE 'SPRINT_BATCH'; ClaudeJobKind ADD VALUE
  'SPRINT_IMPLEMENTATION'; nieuwe enum SprintTaskExecutionStatus; ClaudeJob.lease_until
  + status_lease_until index; SprintRun.previous_run_id (self-relation
  SprintRunChain) voor branch-hergebruik bij resume; nieuwe sprint_task_executions
  tabel met frozen plan_snapshot + verify_required_snapshot per task in scope.
- actions/sprint-runs.ts startSprintRunCore: nieuwe blocker-type 'task_cross_repo'
  voor SPRINT_BATCH (pre-flight rejecteert sprints met cross-repo task_url).
  Bij SPRINT_BATCH: één SPRINT_IMPLEMENTATION ClaudeJob (geen per-task loop).
- actions/sprint-runs.ts resumePausedSprintRunAction: SPRINT_BATCH-pad met
  remaining-execution-check; bij onafgemaakt werk → nieuwe SprintRun met
  previous_run_id + run.branch hergebruikt + nieuwe SPRINT_IMPLEMENTATION-job.
  Oude SprintRun → CANCELLED. Bestaande PBI-49 P0 scope-DONE pad ongewijzigd.
- actions/products.ts updatePrStrategyAction: accepteert SPRINT_BATCH.
- components/products/pr-strategy-select.tsx: drie opties met helptekst,
  gebruikt @prisma/client PrStrategy ipv lokaal type.
- components/sprint/sprint-run-controls.tsx: BLOCKER_LABELS + blockerHref
  voor task_cross_repo.

Migratie applied op Neon. Type-check + 532 tests groen.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* PBI-50 F5: cross-repo blocker test voor SPRINT_BATCH

- task_cross_repo blocker fires bij task.repo_url ≠ product.repo_url
- happy path: tasks zonder repo_url-override of met match → één
  SPRINT_IMPLEMENTATION-job (niet per-task).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* PBI-50 F5: docs/architecture/sprint-execution-modes.md

Vergelijking PER_TASK vs SPRINT_BATCH met trade-offs, datamodel-
toevoegingen (SprintTaskExecution, lease_until, SprintRunChain) en
MCP-tools-matrix per modus. Toegevoegd aan breadcrumb in
docs/architecture.md.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

prisma/migrations/20260507103000_sprint_implementation/migration.sql

@@ -0,0 +1,68 @@
+-- PBI-50: SPRINT_IMPLEMENTATION single-session sprint runner
+-- Adds:
+--  - PrStrategy.SPRINT_BATCH (third option)
+--  - ClaudeJobKind.SPRINT_IMPLEMENTATION (fifth kind)
+--  - SprintTaskExecutionStatus enum
+--  - ClaudeJob.lease_until (for heartbeat-driven stale detection)
+--  - SprintRun.previous_run_id (for branch reuse on resume)
+--  - sprint_task_executions table (frozen scope-snapshot per claim)
+
+-- AlterEnum: PrStrategy ADD VALUE (Postgres requires this outside transaction;
+-- Prisma migrate handles it)
+ALTER TYPE "PrStrategy" ADD VALUE 'SPRINT_BATCH';
+
+-- AlterEnum: ClaudeJobKind ADD VALUE
+ALTER TYPE "ClaudeJobKind" ADD VALUE 'SPRINT_IMPLEMENTATION';
+
+-- CreateEnum
+CREATE TYPE "SprintTaskExecutionStatus" AS ENUM ('PENDING', 'RUNNING', 'DONE', 'FAILED', 'SKIPPED');
+
+-- AlterTable
+ALTER TABLE "claude_jobs" ADD COLUMN     "lease_until" TIMESTAMP(3);
+
+-- AlterTable
+ALTER TABLE "sprint_runs" ADD COLUMN     "previous_run_id" TEXT;
+
+-- CreateTable
+CREATE TABLE "sprint_task_executions" (
+    "id" TEXT NOT NULL,
+    "sprint_job_id" TEXT NOT NULL,
+    "task_id" TEXT NOT NULL,
+    "order" INTEGER NOT NULL,
+    "plan_snapshot" TEXT NOT NULL,
+    "verify_required_snapshot" "VerifyRequired" NOT NULL,
+    "verify_only_snapshot" BOOLEAN NOT NULL DEFAULT false,
+    "base_sha" TEXT,
+    "head_sha" TEXT,
+    "status" "SprintTaskExecutionStatus" NOT NULL DEFAULT 'PENDING',
+    "verify_result" "VerifyResult",
+    "verify_summary" TEXT,
+    "skip_reason" TEXT,
+    "started_at" TIMESTAMP(3),
+    "finished_at" TIMESTAMP(3),
+    "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updated_at" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "sprint_task_executions_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE INDEX "sprint_task_executions_sprint_job_id_order_idx" ON "sprint_task_executions"("sprint_job_id", "order");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "sprint_task_executions_sprint_job_id_task_id_key" ON "sprint_task_executions"("sprint_job_id", "task_id");
+
+-- CreateIndex
+CREATE INDEX "claude_jobs_status_lease_until_idx" ON "claude_jobs"("status", "lease_until");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "sprint_runs_previous_run_id_key" ON "sprint_runs"("previous_run_id");
+
+-- AddForeignKey
+ALTER TABLE "sprint_runs" ADD CONSTRAINT "sprint_runs_previous_run_id_fkey" FOREIGN KEY ("previous_run_id") REFERENCES "sprint_runs"("id") ON DELETE SET NULL ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "sprint_task_executions" ADD CONSTRAINT "sprint_task_executions_sprint_job_id_fkey" FOREIGN KEY ("sprint_job_id") REFERENCES "claude_jobs"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "sprint_task_executions" ADD CONSTRAINT "sprint_task_executions_task_id_fkey" FOREIGN KEY ("task_id") REFERENCES "tasks"("id") ON DELETE CASCADE ON UPDATE CASCADE;