v1.2.0

• Add BatchBulkheadStore::activeCounts(list $names): array — an active-load snapshot for many bulkheads at once, for least-loaded selection among hundreds of candidates without one store round trip per name (#38). All three bundled stores implement it: read-only for slots, 0 for names without active slots, duplicate names collapsed, first-seen order. RedisBulkheadStore does it in one Lua round trip that prunes expired leases and counts every key at the same server TIME (mutually consistent counts; any Redis error propagates, no partial result); APCu and in-memory read per name. Redis Cluster needs a hash tag in keyPrefix ({bulkhead}:) or the multi-key call fails with CROSSSLOT.
• Add BulkheadMultiKeyScriptRunner::runMany(script, keys, args): list<int>, implemented by PredisScriptRunner and PhpRedisScriptRunner. RedisBulkheadStore uses it for activeCounts() and degrades to one activeCount() call per name with a custom single-key BulkheadScriptRunner. Existing interfaces are unchanged.
• Switch the test suite's hand-rolled doubles (anonymous BulkheadStore scripted/throwing/poll-budget fakes and the predis ClientInterface fake) to rasuvaeff/understudy via the rasuvaeff/understudy-testo adapter: scriptedStore(n) is a ->returns(null × n, 'token') chain (last link repeats), the poll-budget fake is ->returns(...)->then()->throws(), an always-full store is a loose double with no stubs, and verification/reset run automatically after each test. Dev-only; no runtime changes.