[launch-core/contracts] Build Rootflow V0 contract support and coverage

[FlowmemoryAI]

Objective

Build the contracts-side support needed for Rootflow V0 and Flow Memory V0 launch readiness.

This is an epic-style launch-core issue. It is not complete when a small PR is opened. The contract work is complete only when it provides concrete evidence for the relevant rows in docs/V0_LAUNCH_ACCEPTANCE.md.

Required reading

• docs/ROOTFLOW_V0.md
• docs/FLOW_MEMORY_V0.md
• docs/V0_LAUNCH_ACCEPTANCE.md
• docs/DECISIONS/rootflow-v0.md
• contracts/FLOWPULSE_SCHEMA.md

Scope

Allowed folders:

• contracts/
• tests/
• foundry.toml
• contract-related decision records if needed

Forbidden unless a separate issue explicitly allows it:

• production deployment config
• tokenomics
• dynamic fees
• production Uniswap v4 hooks
• governance or upgrade framework
• verifier economics

Build requirements

• Harden Rootfield namespace registration behavior.
• Harden root commitment behavior.
• Add or verify parent pulse/root linkage support needed by Rootflow V0.
• Emit enough FlowPulse/Rootfield data for indexer-derived Rootflow transitions.
• Add launch-grade tests for positive and negative paths.
• Preserve the boundary that contracts do not know final txHash or logIndex.
• Document any contract-level assumptions for indexer, crypto, and dashboard agents.

Acceptance evidence

• Contract tests pass.
• docs/V0_LAUNCH_ACCEPTANCE.md rows for Rootfield namespaces, root commitments, parent/child transition support, and FlowPulse linkage have concrete evidence.
• PR summary names remaining incomplete launch-core rows.