chore(devlog): advance the plan submodule to 8f2d930

Adds the codex-rs upstream v2/GPT-Live handoff unit
(_plan/260730_codex_rs_upstream_v2_live_handoff) as a docs-only implementation
unit for a later loop to execute: 000-004 research, 010-050 diff-level phase
designs, 2013 lines across 10 numbered docs.

The pointer moves 7dffc79 -> 8f2d930, which also carries forward two earlier
maintainer triage commits already present in the submodule:
  c0a7962 docs(plan): triage the new 260730 issues and PRs
  4cb86ec docs(plan): add PR #750 to the triage before it goes stale

Gitlink only; no runtime, GUI, docs-site, or workflow files are touched, and the
submodule stays loose per AGENTS.md (ignore = dirty, update = none, no CI
checkout).

Author: lidge-jun