Lab Zero v1.13.0 — tracking-size block tier

• Oversized tracking files now block a commit (the 64 KB size warning gained a hard 128 KB tier). v1.12.0 added a warn-only notice when a staged tracking file (Log/STATUS.md / TASKS.md / PLAN.md / DECISIONS.md) passed 64 KB — and said it never blocks a commit. This adds a second, blocking tier: a tracking file staged over 128 KB now fails the pre-commit hook (whole-file readability is load-bearing — a file that big has stopped being reliably readable in one pass). The 64 KB warn level (LAB_TRACKING_SIZE_WARN_KB) is unchanged; the new block level is LAB_TRACKING_SIZE_BLOCK_KB (default 128, and it can never be set below the warn level). To land an oversized tracking file anyway, bypass the hook with git commit --no-verify. This only fires once a single tracking file crosses 128 KB, so if yours are a normal size nothing changes.