Initial dstalk project: core DLL + CLI + BearSSL TLS

- Core DLL: AI API client (DeepSeek/OpenAI compatible), HTTP(S) via Boost.Beast
- BearSSL vendored as TLS backend (MIT license, replacing OpenSSL)
- CLI frontend with ANSI colors, /help /model /file /save /load commands
- WinHTTP alternative HTTP client for Windows
- GPLv3 license with linking exception
- Build: CMake + Ninja + Clang, dependencies via Conan2

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,29 @@
+build/
+build_test/
+.cache/
+.claude/
+*.exe
+*.dll
+*.lib
+*.so
+*.dylib
+*.obj
+*.o
+*.pdb
+*.ilk
+*.exp
+
+# Conan cache / generated
+deps/.conan/
+
+# tools/ 中的便携工具 (由 setup.bat 下载，不提交)
+tools/cmake/
+tools/ninja/
+tools/llvm/
+tools/conan2/
+
+# IDE
+.vs/
+.vscode/
+.idea/
+*.user