feat(mcp): expose scheduled task run-now

[juliusmarminge]

Part 12/16 of the shared-core and MCP stack. Based on #10561. Next: #10563.

Expose ScheduledTaskService.runNow for tasks in the calling project, using the existing manual-run execution and bookkeeping.

Requires a full-access/default caller. Each call is a new manual run, not an idempotent retry. Returned bookkeeping is not provider turn completion; durable keyed retries and scheduler hardening are separate.

MCP-only rebuild of #8731, preserving attribution to Julius Marminge's original work. Original branches remain available for separate service follow-ups.

Validation: The composed stack passes 94 tests across 12 focused files, including shared core MCP and real MCP/V2 integration, attachment intake, project RPC/service contracts, and client model command selection. Server/contracts/shared/client-runtime typechecks and targeted format/lint/diff checks pass. New behavior coverage lives with the shared operation; no per-tool mock suite was added. Current-head CI is shown below.

Layer size: 3 files, +54/-0. No domain-service production implementation or documentation files change in this MCP layer.

Prepared with Codex in the OpenAI agent runtime.

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This PR adds a new destructive MCP operation that can dispatch scheduled-task provider work and update durable run bookkeeping. Although access is bounded and existing scheduler logic is reused, the new user-facing production workflow has material side effects and warrants human review.

No code changes detected at 06de990. Prior analysis still applies.

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[github-actions]

Thread transfer impact

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