A14-34: ParsSim.R: bitwShiftL overflow silently corrupts the Fitch score at >=31 states

[ms609]

R/ParsSim.R:315 — bitwShiftL(1L, tip_states) returns NA (32-bit integer overflow) for any state code >= 31, silently corrupting the resulting Fitch score computation rather than erroring.

Verified REAL (haiku verifier, code-read).

Fix: guard against tip_states >= 31, or use a wider integer/bitset representation for high state counts.

Filed by /red-team area 14 (opus finder, 2026-08-05).

[ms609]

Working on branch feature/clusterstrings-parssim, worktree ../worktrees/TS-r-utils.