THRIFT-6001: Type remaining core PHP lib methods and fix TException tmethod UUID drift

[sveneld]

Type the remaining untyped methods across core lib classes and fix two real defects surfaced by the typing audit.

Real bug fixes

• TException::$tmethod was missing TType::UUID => 'Uuid' — TBase has had it since THRIFT-5980, but the HackTown-duplicated map on TException drifted. Effect: UUID-typed fields in Thrift exception structs fell through to the slow recursive STRUCT path instead of the scalar fast-path during read/write. Added a unit test (testTmethodMirrorsTBase) guarding parity between the two maps to prevent future drift.

• TMultiplexedProcessor::process() now declares : mixed (was untyped). Return value is propagated from the dispatched underlying processor, whose return shape is generator-emitted; can tighten to : bool once the generator passes through a follow-up PR.

Typing

• TBase::__construct(?array $spec = null, ?array $vals = null)
• TBase::__wakeup(): void
• ThriftClassLoader::registerNamespace(string $namespace, string|array $paths): void
• ThriftClassLoader::registerDefinition(string $namespace, string|array $paths): void
• ThriftClassLoader::register(bool $prepend = false): void
• ThriftClassLoader::loadClass(string $class): void
• ThriftClassLoader::findFileInApcu(string $class): ?string — corrects the previous loose contract; apcu_fetch returns false on cache-miss, so we coerce to null to match the nullable return
• TSocketPool::apcuFetch(string $key, ?bool &$success = null): mixed
• TSocketPool::apcuStore(string $key, mixed $var, int $ttl = 0): bool
• TConstant::get(string $constant): mixed

Validation (Docker thrift-php-dev:local)

• phpcs — 0 errors
• phpstan (level 5) — 0 errors
• phpunit Unit Suite — 636 tests (+1 new tmethod-parity guard), 0 failures
• phpunit Integration Suite — 108 tests, 0 failures

Follow-up to THRIFT-6000 within the umbrella THRIFT-5960.

• Apache Jira ticket — THRIFT-6001
• PR title follows the pattern "THRIFT-NNNN: …"
• Squashed to a single commit
• TBase::__construct signature change widens null (was untyped, now ?array); backwards compatible — any existing caller that passed null or an array continues to work, while passing a different scalar now fails loudly under strict types instead of silently mis-iterating.

Generated-by: Claude Opus 4.7