docs: add missing stdlib modules and update language reference
Stdlib.md:
- Add Std::Task (thread spawn/join/sleep)
- Add Std::Channel (generic channels + wrappers)
- Add Std::Net (TCP sockets)
- Add Std::Json (parser/serializer)
- Add Std::Crypto (SHA-256, HMAC, Base64, random)
- Add Std::Fmt (formatting wrappers)
- Add Std::Math (Sqrt, Pow, Abs, Min, Max)
- Add String_FromFloat to String docs
- Update Future Modules list
LanguageRef.md:
- Add Concurrency section (threads + channels)
- Update Ownership with move semantics and own T
BuildAndTest.md:
- Add libssl-dev/openssl prerequisite note
- Mention -lcrypto auto-linking
dimgigov
809785711c