Route OSInfo.getArchName() through LlamaSystemProperties.getOsinfoArchitecture()

OSInfo.getArchName() read the override system property via a hard-coded
string literal:

  String override = System.getProperty("net.ladenthin.llama.osinfo.architecture");

bypassing LlamaSystemProperties.getOsinfoArchitecture(), the registry-side
getter built specifically to be the single source of truth for that
property name. The deep scan that produced the README System Properties
Reference (e36f631) surfaced this as one of two registry-bypass smells;
fixing it here closes the first.

Routing through the registry keeps the property name in exactly one
place, mirrors the recent BAF Radix.HEX consolidation (where every
literal '16' radix was replaced by a single Radix.HEX constant), and
means future renames or scope tightenings of the property only have to
land in LlamaSystemProperties.

Tests: OSInfoTest 16/16 pass (the override-set branch is already
covered by the test that sets ARCH_OVERRIDE_PROP); mvn compile clean.

Author: claude

src/main/java/net/ladenthin/llama/OSInfo.java

@@ -387,7 +387,7 @@ static String resolveArmArchType() {
      * @return the canonical architecture folder name
      */
     public static String getArchName() {
-        String override = System.getProperty("net.ladenthin.llama.osinfo.architecture");
+        String override = new LlamaSystemProperties().getOsinfoArchitecture();
         if (override != null) {
             return override;
         }