General optimize

[juny2400]

1. Performance Optimizations

• Compile-time-prime Barrett kernels (ModArith.hpp, PresetTraits.hpp): For compile-time presets (P != PRESET_EMPTY, u64), each polyunit's prime / Barrett ratio / shift is folded into immediates instead of reloaded from runtime members. Yields ~1.25–1.3x on the Barrett multiply path. Dispatch via mulPolyP / mulPolyConstP safely falls back to the runtime path when no prime matches.
• Rewritten poly add/sub/mul loops (ModArith.cpp): Dropped collapse(2) in favor of raw-pointer affine loops with the prime hoisted for better vectorization. Unified the lazy-reduction variant via a LazyConstSub template parameter.
• Precomputed CRT constants in Decryptor (Decryptor.hpp/.cpp): The two-prime CRT Bezout coefficients (modular inverses) are computed once in the constructor, removing ~60 modular multiplications per inverse from the decrypt hot path.
• MSVC hardware intrinsics (Basic.hpp): u128 multiply/divide now use _umul128/_udiv128 at runtime while staying constexpr-compatible via __builtin_is_constant_evaluated().
• Reused encode scratch buffers in Encryptor: avoids per-encrypt reallocation.

2. Seed-Only Ciphertext Feature

• Added CipherSeedMode (NONE / UNIFORM / PUBLICKEY) — stores only the RNG seed instead of the full a part of a ciphertext, reducing serialized size.
• New EncryptOptions: SeedOnlyA, ASeed (fixed a seed), and ErrorSeed (deterministic noise, for testing).
• EncryptorT::completeCiphertext() (two overloads: key-free UNIFORM / encryption-key PUBLICKEY) and the expandUniformAxInplace() helper regenerate the a part on demand.
• New CiphertextT API: hasSeed / getSeed / setSeed / flushSeed / seedMode / flushAx / isAxFlushed.

3. Serialization (DebFBType.fbs)

• Added seed and seed_mode fields to the FlatBuffers s
• Narrowed field widths for size: preset/encoding/type → uint8, ntt_info → int8, and renamed Sk.seeds → seed.

4. Build / Docs / Examples

• New CMake options: DEB_SERIALIZE_API, DEB_SUPPORT_U64/U32, DEB_MEMORY_ALIGN_SIZE, DEB_EXT_LIB_FOR_SECURE_ZERO.
• Added DEB_ARCH=x86-64-v3 to the benchmark preset andbench_ct_vs_rt.cpp, CT vs RT path comparison) with nogoogle/benchmark dependency.
• New example SeedOnlyCiphertext.cpp, new tests (EnDec, and README updates.

▎ ⚠️ Security note: Reusing the same ErrorSeed across — intended for testing/reproducibility only.

[leejonghyeong]

doxygen docs seems different (from git diff private/main -- CMakeLists.txt)

     doxygen_add_docs(
       deb_doc
       ${CMAKE_CURRENT_SOURCE_DIR}/include/deb/CKKSTypes.hpp
-      ${CMAKE_CURRENT_SOURCE_DIR}/include/deb/utils/Constant.hpp
+      ${CMAKE_CURRENT_SOURCE_DIR}/include/deb/Constant.hpp
+      ${CMAKE_CURRENT_SOURCE_DIR}/include/deb/Context.hpp