chore: publish 4.0.0-rc.1 #389

Why

Release candidates go on next (master plan Decision 1).

In scope

Cut, publish, release notes.

Out of scope

latest.

Acceptance criteria

• npx @pacphi/agentic-kit@4.0.0-rc.1 --version prints the version
• Upstream items still waiting move to v4.1.0 (Decision 3a)

Dependencies

Blocked by: #388, #382, #383, #213

Blocks: #390

Plan

• Release: 4.0.0-rc.1
• Size: size:S · Workstream: ws:release
• Epic: chore: 4.0 release train (epic) #304
• Card: REL-RC1 in the card inventory
• Sources: Master plan (docs(plans): v4 GA master plan, supersession ledger and v5 registers #290) Decisions 1 and 3a

Verification

• npx @pacphi/agentic-kit@4.0.0-rc.1 --version