Add freeze MPQ unit tests and fix 64-bit memory bugs

[armoha]

Adds a mpq_unit_tests target (doctest) for the freeze MPQ code and fixes the
real bugs the new tests exposed. CI runs it on Windows/macOS/Ubuntu per push and PR.

Tests

• New mpq/test/test_keycalc_crypt.cpp: T/mix known answers, mix/unmix
  roundtrip, HashString semantics, Encrypt/Decrypt roundtrip,
  GetFileDecryptKey recovery, keycalc determinism + input guards,
  deterministic garbagify overload.
• Existing compression roundtrip test now actually runs (it was never wired
  into CMake) — and it caught a heap overflow on first run.
• test_cmpdcmp.cpp: compare via size + memcmp instead of CHECK(str == str);
  doctest has no std::string overload, so the latter instantiates
  operator<<(ostream, string), which fails to link on Xcode Clang.

Fixes (behavior-preserving except the overflow)

• Heap overflow in PKWARE explode/implode on 64-bit: the work structs
  assume 32-bit long/pointers and outgrew EXP_BUFFER_SIZE/CMP_BUFFER_SIZE.
  Buffers enlarged with compile-time fit asserts (exp.c, imp.c, pklib.h).
• uLong/LPDWORD width mismatch in Deflate/Inflate (scomp.cpp):
  casting 32-bit LPDWORD to 64-bit unsigned long* corrupts memory on LP64.
  Now bounces through a uLong temp.
• keycalc: null/tiny-table/zero-sector guards (throw instead of UB),
  explicit wrapping-arithmetic docs + fixed bit-identity notes vs freeze/.
• GetFileDecryptKey: RAII buffer (exception-safe), null check, memcpy
  instead of unaligned uint32_t* dereference.
• garbagifyHashTable: deterministic (table, max, gen&) overload for tests;
  production path unchanged (still random_device).
• Remove unimplemented getFileCount/getBlockEntryCount declarations;
  catch (const std::exception&) instead of slicing catch (runtime_error);
  system("pause") is _WIN32-only.

CI

• New .github/workflows/test.yml: builds + runs mpq_unit_tests on the
  3-OS matrix using a bare uv venv (no full dep sync needed).
• FREEZE_BUILD_TESTS option (default ON) in mpqprt/CMakeLists.txt.

Verification

• mpq_unit_tests: 8/8 cases, 61/61 assertions pass (also clean under ASan).
• lib/freezeMpq.so rebuilt with Python 3.14t; full ed_profile run passes
  (9.25s, no regression vs 9.23s before).