Fix stale-turn dynamic tracker tool calls

[yvette-carlisle]

Summary

• accept dynamic tool calls when the request is bound to the active thread even if the payload turnId differs from the active turn/start id
• keep wrong-thread dynamic tool calls fail-closed and preserve declared tool/namespace/response validation
• update app-server spec and add regression coverage for the stale-turn tracker-tool failure

Validation

• cargo test -p decodex dynamic_tool_call --all-features
• cargo make fmt
• cargo make lint-fix
• cargo make test
• cargo make check
• cargo run -p decodex --bin decodex -- probe stdio://