docs: add Authentication, Clustering, JetStream, Monitoring overviews; update existing docs
New files:
- Documentation/Authentication/Overview.md — all 7 auth mechanisms with real source
snippets (NKey/JWT/username-password/token/TLS mapping), nonce generation, account
system, permissions, JWT permission templates
- Documentation/Clustering/Overview.md — route TCP handshake, in-process subscription
propagation, gateway/leaf node stubs, honest gaps list
- Documentation/JetStream/Overview.md — API surface (4 handled subjects), streams,
consumers, storage (MemStore/FileStore), in-process RAFT, mirror/source, gaps list
- Documentation/Monitoring/Overview.md — all 12 endpoints with real field tables,
Go compatibility notes
Updated files:
- GettingStarted/Architecture.md — 14-subdirectory tree, real NatsClient/NatsServer
field snippets, 9 new Go reference rows, Channel write queue design choice
- GettingStarted/Setup.md — xUnit 3, 100 test files grouped by area
- Operations/Overview.md — 99 test files, accurate Program.cs snippet, limitations
section renamed to "Known Gaps vs Go Reference" with 7 real gaps
- Server/Overview.md — grouped fields, TLS/WS accept path, lame-duck mode, POSIX signals
- Configuration/Overview.md — 14 subsystem option tables, 24-row CLI table, LogOverrides
- Server/Client.md — Channel write queue, 4-task RunAsync, CommandMatrix, real fields
All docs verified against codebase 2026-02-23; 713 tests pass.
e553db6d40