docs(c4): fix 3a — remove AOP @Around from secFilter→permAspect rel label

The filter chain doesn't invoke the AOP aspect directly — Spring Security
hands off to the servlet and AOP intercepts at the method level. The label
implied a direct invocation chain that doesn't exist.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/architecture/c4-diagrams.md

@@ -80,7 +80,7 @@ C4Component
     }
 
     Rel(frontend, secFilter, "All requests", "HTTP / Basic Auth header")
-    Rel(secFilter, permAspect, "Authenticated requests proceed to guarded methods", "AOP @Around")
+    Rel(secFilter, permAspect, "Authenticated requests reach guarded service methods", "")
     Rel(secConf, userDetails, "Wires as UserDetailsService", "")
     Rel(userDetails, db, "Loads user by email", "JDBC")
 ```