fix(arch): permit Server layer to access Value (pre-existing #266 regression)

LlamaArchitectureTest.layeredArchitecture was already failing on main (not
introduced by the TTS work): the streaming-completions merge (#266) added
LlamaModelBackend (server layer) reads of StopReason / LlamaOutput (value layer),
but the Value layer's mayOnlyBeAccessedByLayers list — documented as "the EXACT
set of packages that reference it today" — was not updated. Add "Server" to it,
the same maintenance the rule's own javadoc prescribes.

Unrelated to TTS but folded in here because it blocks PR #268's CI; kept as its
own commit so it can be cherry-picked to main independently.

Author: vaijurao

src/test/java/net/ladenthin/llama/LlamaArchitectureTest.java

@@ -127,7 +127,7 @@ public class LlamaArchitectureTest {
             .whereLayer("Parameters")
             .mayOnlyBeAccessedByLayers("Api", "Loader", "Server")
             .whereLayer("Value")
-            .mayOnlyBeAccessedByLayers("Api", "Json", "Parameters")
+            .mayOnlyBeAccessedByLayers("Api", "Json", "Parameters", "Server")
             .whereLayer("Callback")
             .mayOnlyBeAccessedByLayers("Api")
             .whereLayer("Exception")