Prevent type model compiler stack overflow

[kevinherron]

Summary

• replace recursive declaration traversal with an explicit depth-first stack
• preserve deterministic child ordering, cycle tracking, override precedence, and post-order member-type expansion
• ensure over-depth models produce DEPTH_LIMIT_EXCEEDED instead of exhausting the JVM stack

Root cause

Each declaration level added both walkChildren and processChild frames. On JVMs with less usable thread stack, the native stack could be exhausted before the configured 512-level guard ran. This made the failure platform- and workload-sensitive: the focused test could pass while the full reactor failed.

Validation

• mise exec -- mvn -q spotless:apply
• mise exec -- mvn -q -pl opc-ua-sdk/sdk-server -am test -Dtest=TypeModelCompilerTest
• mise exec -- mvn -q clean compile
• mise exec -- mvn -q verify