fix(abi-verify): tolerate non-canonical Zig switch arm false shorthand

[hyperpolymath]

abi-verify's Zig FFI parser bombed on 5 cartridges' isValidTransition switch arms because their terminal-state arm body is the literal false (no outgoing transitions allowed) rather than the canonical to == .<v> chunk form:

fn isValidTransition(from: BspState, to: BspState) bool {
    return switch (from) {
        ...
        .exited => false,   // <-- parser bombed here
    };
}

The Zig is well-formed and the semantics ("empty allowed-set") are clear; the verifier just didn't accept the shorthand.

parse_arm_targets now detects this form (body trimmed of trailing ,/; and whitespace equals false) and returns the empty vec — equivalent to the "this state has no allowed outgoing transitions" manifest semantics, which is exactly what the cartridges intend.

End-to-end verified against the 5 cartridges named in the issue (after a fresh cargo build --release):

bsp-mcp → parses cleanly; surfaces real drift on BspCapability
container-mcp → abi-verify OK
dap-mcp → parses cleanly; surfaces real drift on StepGranularity
lsp-mcp → parses cleanly; surfaces real drift on CompletionKind
vault-mcp → parses cleanly; surfaces real drift on IdentityType

All 5 now produce either exit 0 (clean) or a real drift diagnosis, which is precisely the acceptance criterion in iseriser#19. The post-parse drift findings are separate per-cartridge issues — not verifier defects — and out of scope for this PR.

44 lib tests + 9 integration tests pass.

Refs hyperpolymath/standards#92 (Phase 2 allowlist expansion). Refs #19.

Summary

Changes

RSR Quality Checklist

Required

• Tests pass (just test or equivalent)
• Code is formatted (just fmt or equivalent)
• Linter is clean (no new warnings or errors)
• No banned language patterns (no TypeScript, no npm/bun, no Go/Python)
• No unsafe blocks without // SAFETY: comments
• No banned functions (believe_me, unsafeCoerce, Obj.magic, Admitted, sorry)
• SPDX license headers present on all new/modified source files
• No secrets, credentials, or .env files included

As Applicable

• .machine_readable/STATE.a2ml updated (if project state changed)
• .machine_readable/ECOSYSTEM.a2ml updated (if integrations changed)
• .machine_readable/META.a2ml updated (if architectural decisions changed)
• Documentation updated for user-facing changes
• TOPOLOGY.md updated (if architecture changed)
• CHANGELOG or release notes updated
• New dependencies reviewed for license compatibility (PMPL-1.0-or-later / MPL-2.0)
• ABI/FFI changes validated (src/interface/abi/ and src/interface/ffi/ consistent)

Testing

Screenshots