fix(runtime): start actor effects eagerly

[cevr]

Summary

Start state and background Effects eagerly. Complete their synchronous setup before actor state becomes visible to subscribers.

Closes #52.

Changes

• Start .spawn(), .task(), .timeout(), and .background() Effect setup in the actor lifecycle turn.
• Keep state scope and actor scope as the only Effect lifetime owners.
• Register deferred ask replies before state Effect setup.
• Preserve the original cause for synchronous state Effect defects.
• Keep supervised startup defects under supervisor ownership.
• Add direct actor, task, Atom, defect, reply, cleanup, order, and supervision tests.

Compatibility

A task that completes in its first Effect slice can enqueue its result before a caller sends its next event. A caller that must observe a transient state must start its wait before it sends the event.

Inspector handlers remain ordered and awaited. A suspending Inspector can delay Effect setup.

Test plan

• bun run gate
• 332 package tests
• Typecheck
• Effect lint
• Format
• Build
• Core example gate
• React example gate
• Solid example gate

Design review

Counsel selected the internal eager-start design. It rejected a public option and a second readiness protocol. Review receipt: /tmp/counsel/rifts-bite-18966-a73c67f5/20260901-121525-codex-to-claude-865753/claude.md.