[flows-tinyflows] copilot: ProposeWorkflow and RunFlow tools, backend repair message, per-call port context #9

Moved from tinyhumansai#153, which is closed in favour of this issue. Part of tinyhumansai/openhuman#8055.

• Add ProposeWorkflowTool (upstream ReviseWorkflowTool with revision=false, description from render_node_kinds_required; needs only BuilderGates + NodeKindSource) and RunFlowTool (needs a new FlowStore::run_detached(flow_id, input, inputs)), moving host flows/tools.rs (374 lines). Tool names propose_workflow/run_flow and their JSON schemas unchanged.
• Move is_backend_or_infrastructure_failure/backend_repair_message (host flows/ops/builder.rs:501-528) into tinyflows_copilot::fallback.
• Ports carry a per-call context so hosts stop relying on an ambient dispatch context (openhuman#7801; host builder_host.rs:42 vs tools.rs:126).

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-copilot/src/tools/, crates/tinyflows-copilot/src/fallback.rs
• Research: Host flows/tools.rs, ops/builder.rs; openhuman#7801.
• Workflow: an implementing-an-epic step; follow migrate-to-submodule (upstream PR → patch release → OpenHuman gitlink bump + digest re-pin).
• Subagent: tdd-implementer.
• Dependencies: none.

Parent: tinyhumansai/openhuman#8055