fix(agent-manager): transfer wrapper registry identity

[codeaholicguy]

Summary

• atomically transfer same-type registry names from wrapper PIDs to detected child PIDs during discovery batches
• preserve managed tmux and start metadata while refreshing child session fields
• keep explicit registration, cross-type conflicts, and duplicates introduced within one batch strict
• add TDD regressions and lifecycle documentation for the Gemini uniqueness failure

Validation

• npm run test:coverage --workspace @ai-devkit/agent-manager: 521 tests passed; coverage thresholds passed
• npm test --workspace ai-devkit -- agent.service.test.ts agent.test.ts: 104 tests passed
• npm run typecheck --workspace @ai-devkit/agent-manager
• npm run lint --workspace @ai-devkit/agent-manager
• npm run build: all six projects built
• npx ai-devkit@latest lint --feature agent-registry-wrapper-transfer
• built local agent list --json smoke check passed against the previously failing registry

Risk

Low. Identity transfer is limited to names owned before the batch by another PID of the same agent type. Single registration and unrelated duplicate detection remain strict.