feat: add method call support and analyzeFull

- Add analyzeFull() to return Sema context with method table
- Improve method call desugaring: obj.method() → Type_method(obj)
- Search methodTable by method name when type inference fails
- Add methods.bux example demonstrating struct with extend blocks
- Use analyzeFull in cli.nim for proper method resolution

src/sema.nim

@@ -573,3 +573,11 @@ proc analyze*(modu: Module): SemaResult =
   sema.collectGlobals()
   sema.checkBodies()
   result = SemaResult(diagnostics: sema.diagnostics)
+
+proc analyzeFull*(modu: Module): tuple[result: SemaResult, sema: Sema] =
+  ## Analyze module and return both result and full Sema context
+  ## Use this when you need the Sema for lowering (method table, etc.)
+  var sema = Sema(module: modu, globalScope: newScope())
+  sema.collectGlobals()
+  sema.checkBodies()
+  result = (SemaResult(diagnostics: sema.diagnostics), sema)