[flows-tinyflows] flows+cron: split oversized KEEP files #67

Moved from tinyhumansai#8045, which is closed in favour of this issue. Part of tinyhumansai#8055.

Mechanical splits, no behaviour change:

• cron/scheduler.rs (505) → scheduler/{dispatcher,live_agents,manual_run}.rs.
• cron/schemas.rs (492) → declarations vs handlers.
• flows/schemas.rs (538) → move the registered-controller vec (:349-496) into the schemas/ groups.
• flows/schemas_handlers.rs (568, include!d) → schemas/handlers/{definition,run,builder,draft}.rs.
• flows/tinyflows/caps/agent.rs (578) → move AgentRoute, route_for_agent_ref, route_custom_entry_lookup, harness_model_default_override (:121-170,:289-306) to flows/agent_route.rs.

ops/builder.rs and ops/builder_gates.rs are split by #69 / #74. RPC names unchanged.

Done when: the rows above are gone from crates/openhuman-core/src/flows/ / crates/openhuman-core/src/cron/ (moved, deleted or reduced to the stated host adapter), with their tests moved alongside. Gates: cargo check (root + crates/openhuman-app), pnpm rust:layout, node scripts/ci/check-feature-forwarding.mjs, pnpm debug rust flows|cron, and the touched crates' tests. RPC namespace strings, model-facing tool names and DomainEvent variant names stay unchanged.

Agent brief

• Files to consider (paths under crates/openhuman-core/src/ unless rooted): cron/scheduler.rs, cron/schemas.rs, flows/schemas.rs, flows/schemas_handlers.rs, flows/tinyflows/caps/agent.rs
• Research: None.
• Workflow: an implementing-an-epic step.
• Subagent: tdd-implementer.
• Dependencies: [flows-tinyflows] flows delete: shims, re-exports and dead code #58, [flows-tinyflows] cron delete: completion_owner side-channel and dead code #60.

Blocked by #58
Blocked by #60
Parent: tinyhumansai#8055