docs: extend effectful program lecture citations

[huangruiteng]

Summary

Extend the public "Agent Loop 是 effectful program(1)" citation to the
remaining "Harness Is the Effectful Program" anchors.

• docs/architecture.md
• docs/reference/effect-interpreter-packet.md
• docs/product/core-control-plane/README.md

No runtime behavior changes.

Validation

• docs-governance-smoke: passed.
• loopx canary premerge --from-git-diff: passed, self_merge_allowed=true,
  0 manual holds.
• Public boundary scan: passed; no internal lecture links added.

Routing

• continuation-policy: independent_handoff
• excluded-agent: codex-quality-qualification
• claimed-by: codex-side-bypass

[huangruiteng]

Approval conclusion (author-owned PR; GitHub blocks formal self-approval)

Reviewed exact head bdc110c. No blocking findings.

The PR adds the public "Agent Loop 是 effectful program(1)" citation to the
remaining "Harness Is the Effectful Program" anchors in architecture, packet
reference, and core control-plane README. Docs only, no runtime behavior
changes.

Validation

• docs-governance-smoke: passed.
• loopx canary premerge --from-git-diff: passed, self_merge_allowed=true,
  0 manual holds.
• GitHub build and dependency-review on this head: pass.
• Public boundary scan: passed; no internal lecture links added.

Merge decision: approved after reviewer.