[flows-tinyflows] Runs surface: StartRun, PollRun, CancelRun with module-owned run rows and dedup settle (slice 4b) #5

Moved from tinyhumansai#149, which is closed in favour of this issue. Part of tinyhumansai/openhuman#8055.

Serve StartRun/PollRun/CancelRun (crates/tinyflows-bus/src/runs.rs, skeleton) on the module's executor, over CapsHost (#4) and the document port.

Gaps from the host (flows/ops/{run,execution,run_rows,run_management}.rs, flows/bus/dedup_commit.rs):

• StartRun takes declared inputs, a FlowRunTrigger, flow/origin context, and returns prep errors (compat, compile, resolve_inputs) synchronously.
• PollRun events include step persistence and graph observations plus graph_run_id (host Langfuse export and FlowRunProgress projection).
• Run-row bookkeeping (insert_flow_run, finish_flow_run, upsert_flow_run_step, run_summary::settle_steps) happens in the module.
• Dedup settle at run end inside the module against the executed graph (dedup_settle::settle), replacing the host's DedupCommitSubscriber (which reads the current saved graph, dedup_commit.rs:179-203).
• Run timeout — epic open decision 3.

Follow migrate-to-submodule (OpenHuman .claude/skills/): upstream PR → patch release → OpenHuman gitlink bump + registry digest re-pin. Design reference: docs/tinyflows-bus-design.md.

Done when: merged in tinyhumansai/tinyflows with wire tests for every new or changed contract type, released (patch), and the contract version bumped where a served shape changed. Gates: cargo fmt --all -- --check, cargo clippy --all-targets --all-features -- -D warnings, cargo test --all-features in tinyhumansai/tinyflows. OpenHuman adoption is a separate leaf of the epic.

Agent brief

• Files to consider (paths in tinyhumansai/tinyflows): crates/tinyflows-bus/src/runs.rs, crates/tinyflows-module/src/, crates/tinyflows-catalog/src/run_summary.rs
• Research: Host files above; decision 3.
• Workflow: an implementing-an-epic step; follow migrate-to-submodule (upstream PR → patch release → OpenHuman gitlink bump + digest re-pin).
• Subagent: tdd-implementer.
• Dependencies: [flows-tinyflows] Serve the CapsHost callback interface (slice 4a) #4, [flows-tinyflows] Catalog surface: drafts, suggestions and run reads #2.

Blocked by #4
Blocked by #2
Parent: tinyhumansai/openhuman#8055