feat: add structured logging, Shouldly assertions, CPM, and project documentation

- Add Microsoft.Extensions.Logging + Serilog to NatsServer and NatsClient
- Convert all test assertions from xUnit Assert to Shouldly
- Add NSubstitute package for future mocking needs
- Introduce Central Package Management via Directory.Packages.props
- Add documentation_rules.md with style guide, generation/update rules, component map
- Generate 10 documentation files across 5 component folders (GettingStarted, Protocol, Subscriptions, Server, Configuration/Operations)
- Update CLAUDE.md with logging, testing, porting, agent model, CPM, and documentation guidance

tests/NATS.Server.Tests/SubListTests.cs

@@ -15,9 +15,9 @@ public class SubListTests
         sl.Insert(sub);
 
         var r = sl.Match("foo.bar");
-        Assert.Single(r.PlainSubs);
-        Assert.Same(sub, r.PlainSubs[0]);
-        Assert.Empty(r.QueueSubs);
+        r.PlainSubs.ShouldHaveSingleItem();
+        r.PlainSubs[0].ShouldBeSameAs(sub);
+        r.QueueSubs.ShouldBeEmpty();
     }
 
     [Fact]
@@ -27,7 +27,7 @@ public class SubListTests
         sl.Insert(MakeSub("foo.bar"));
 
         var r = sl.Match("foo.baz");
-        Assert.Empty(r.PlainSubs);
+        r.PlainSubs.ShouldBeEmpty();
     }
 
     [Fact]
@@ -37,9 +37,9 @@ public class SubListTests
         var sub = MakeSub("foo.*");
         sl.Insert(sub);
 
-        Assert.Single(sl.Match("foo.bar").PlainSubs);
-        Assert.Single(sl.Match("foo.baz").PlainSubs);
-        Assert.Empty(sl.Match("foo.bar.baz").PlainSubs);
+        sl.Match("foo.bar").PlainSubs.ShouldHaveSingleItem();
+        sl.Match("foo.baz").PlainSubs.ShouldHaveSingleItem();
+        sl.Match("foo.bar.baz").PlainSubs.ShouldBeEmpty();
     }
 
     [Fact]
@@ -49,9 +49,9 @@ public class SubListTests
         var sub = MakeSub("foo.>");
         sl.Insert(sub);
 
-        Assert.Single(sl.Match("foo.bar").PlainSubs);
-        Assert.Single(sl.Match("foo.bar.baz").PlainSubs);
-        Assert.Empty(sl.Match("foo").PlainSubs);
+        sl.Match("foo.bar").PlainSubs.ShouldHaveSingleItem();
+        sl.Match("foo.bar.baz").PlainSubs.ShouldHaveSingleItem();
+        sl.Match("foo").PlainSubs.ShouldBeEmpty();
     }
 
     [Fact]
@@ -60,9 +60,9 @@ public class SubListTests
         var sl = new SubList();
         sl.Insert(MakeSub(">"));
 
-        Assert.Single(sl.Match("foo").PlainSubs);
-        Assert.Single(sl.Match("foo.bar").PlainSubs);
-        Assert.Single(sl.Match("foo.bar.baz").PlainSubs);
+        sl.Match("foo").PlainSubs.ShouldHaveSingleItem();
+        sl.Match("foo.bar").PlainSubs.ShouldHaveSingleItem();
+        sl.Match("foo.bar.baz").PlainSubs.ShouldHaveSingleItem();
     }
 
     [Fact]
@@ -75,7 +75,7 @@ public class SubListTests
         sl.Insert(MakeSub(">", sid: "4"));
 
         var r = sl.Match("foo.bar");
-        Assert.Equal(4, r.PlainSubs.Length);
+        r.PlainSubs.Length.ShouldBe(4);
     }
 
     [Fact]
@@ -84,10 +84,10 @@ public class SubListTests
         var sl = new SubList();
         var sub = MakeSub("foo.bar");
         sl.Insert(sub);
-        Assert.Single(sl.Match("foo.bar").PlainSubs);
+        sl.Match("foo.bar").PlainSubs.ShouldHaveSingleItem();
 
         sl.Remove(sub);
-        Assert.Empty(sl.Match("foo.bar").PlainSubs);
+        sl.Match("foo.bar").PlainSubs.ShouldBeEmpty();
     }
 
     [Fact]
@@ -99,19 +99,19 @@ public class SubListTests
         sl.Insert(MakeSub("foo.bar", queue: "loggers", sid: "3"));
 
         var r = sl.Match("foo.bar");
-        Assert.Empty(r.PlainSubs);
-        Assert.Equal(2, r.QueueSubs.Length); // 2 queue groups
+        r.PlainSubs.ShouldBeEmpty();
+        r.QueueSubs.Length.ShouldBe(2); // 2 queue groups
     }
 
     [Fact]
     public void Count_tracks_subscriptions()
     {
         var sl = new SubList();
-        Assert.Equal(0u, sl.Count);
+        sl.Count.ShouldBe(0u);
 
         sl.Insert(MakeSub("foo", sid: "1"));
         sl.Insert(MakeSub("bar", sid: "2"));
-        Assert.Equal(2u, sl.Count);
+        sl.Count.ShouldBe(2u);
 
         sl.Remove(MakeSub("foo", sid: "1"));
         // Remove by reference won't work — we need the same instance
@@ -123,9 +123,9 @@ public class SubListTests
         var sl = new SubList();
         var sub = MakeSub("foo");
         sl.Insert(sub);
-        Assert.Equal(1u, sl.Count);
+        sl.Count.ShouldBe(1u);
         sl.Remove(sub);
-        Assert.Equal(0u, sl.Count);
+        sl.Count.ShouldBe(0u);
     }
 
     [Fact]
@@ -136,13 +136,13 @@ public class SubListTests
 
         // Prime the cache
         var r1 = sl.Match("foo.bar");
-        Assert.Single(r1.PlainSubs);
+        r1.PlainSubs.ShouldHaveSingleItem();
 
         // Insert a wildcard that matches — cache should be invalidated
         sl.Insert(MakeSub("foo.*", sid: "2"));
 
         var r2 = sl.Match("foo.bar");
-        Assert.Equal(2, r2.PlainSubs.Length);
+        r2.PlainSubs.Length.ShouldBe(2);
     }
 
     [Fact]
@@ -154,6 +154,6 @@ public class SubListTests
         sl.Insert(MakeSub("foo.bar.*", sid: "3"));
 
         var r = sl.Match("foo.bar.baz");
-        Assert.Equal(3, r.PlainSubs.Length);
+        r.PlainSubs.Length.ShouldBe(3);
     }
 }