Adopt app-server notification turn ids

[yvette-carlisle]

Summary

• adopt same-thread notification turn ids when they differ from turn/start response ids
• persist the adopted id into the run recorder/state store so completion and goal readbacks stay aligned
• add a fake app-server regression case and update the app-server protocol spec

Root cause

Decodex tolerated app-server turn id drift for dynamic tracker tool calls, but the completion loop still filtered turn/completed against the turn/start response id. Same-thread completion notifications were recorded as protocol events but ignored as active turn completion, so phase goal readback did not run and lanes could stay red in agent_run/repo_gate.

Validation

• cargo test -p decodex agent::app_server::tests::phase_goal -- --nocapture
• cargo test -p decodex agent::app_server::tests:: -- --nocapture
• rustup run nightly cargo fmt --all -- --check
• cargo make fmt-check
• git diff --check
• cargo make test
• semantic drift audit for app-server spec/code/test claims