[F2] Owner-aware git-identity.sh

[twistedmelonman]

Latent hazard only, not urgent. Do after I0. See docs/STATUS.md, "Runs in parallel with W."

[twistedmelonman]

Resume note (parked 2026-09-30)

• What: [F2] make git-identity.sh owner-aware.
• Where it stopped: not started; a latent hazard only, not urgent. Explicitly sequenced to happen after [I0] CLAUDE_CONFIG_DIR billing-verification script #150 (I0).
• First step: once [I0] CLAUDE_CONFIG_DIR billing-verification script #150 lands, read docs/STATUS.md ("Runs in parallel with W") for the F2 spec and start there.