docs: dispatch SP-02a from pinned implementation base

[rroojrooj]

Summary

• pin PR docs: accept detailed SP-02a implementation plan #44 merge 2dd82c7 as the exact reviewed SP-02a implementation base
• record Windows CI and post-merge 382/382 verification
• assign and dispatch the isolated implementation lane
• mark SP-02a in progress while keeping SP-02b blocked

Verification

• npm test: 382 passed, 0 failed on merged plan tree
• implementation-lane baseline: 382 passed, 0 failed
• git diff --check