fix(ci): restore green main after merge skew and new advisory (#8277)

Main CI has been red since c09730e87 (#8223). The Mobile and Security
checks fail on main, and Docker image fails because it requires a green
CI run for the same commit. Locally, the pre-push Rust lane also failed
on load-sensitive `buzz-acp` timing tests. This PR fixes all three so
main passes locally and on GitHub.

- **Mobile:** #8223 was tested against a base from before #8206, which
removed `buzzDevPushAppProfile` and app-profile selection. Its new
`notification_toggle_test.dart` still put `appProfile` in the native
grant map, so the merged tree doesn't compile. This removes the stale
field.
- **Security:** cargo-deny now reports
[RUSTSEC-2024-0449](https://rustsec.org/advisories/RUSTSEC-2024-0449)
(`unsafe-libyaml` is unmaintained), which comes in through `serde_yaml`.
It's an unmaintained notice, not a vulnerability. The `serde_yaml_ng`
fork depends on the same crate, so removing it means migrating YAML
parsing in five crates. Like the existing unmaintained entries, it goes
in `deny.toml` with a reason.
- **buzz-acp test flakes:** the `spawn_script` test helper returned
before bash was running, and the timing tests started their idle clock
right away. Under full-suite load, process startup took longer than the
idle windows. `keepalive_resets_idle_past_deadline`,
`idle_resets_on_stdout_activity` and
`acp_steer_request_omits_expected_run_id_and_carries_session_and_prompt`
failed this way across three pre-push runs. The helper now has the
script print a ready line and consumes it before returning. The
keepalive loops also use brace expansion instead of `$(seq)`, which
avoids an extra process launch before the first line. The keepalive test
now uses a 250ms idle window with a 750ms floor. Both tests still fail
if keepalives don't reset the idle clock.

### Validation
- `cargo-deny check advisories` passes with this `deny.toml` and fails
on main's.
- The `notification_toggle_test.dart` tests and `flutter analyze` pass.
- `cargo test -p buzz-acp --lib` passes all 1055 tests.
- The `acp::tests` suite passed 20 of 20 runs with 4 concurrent copies
over 5 rounds. Under the same load, the version without the
brace-expansion change failed every run.
- All pre-push hooks pass on 5dbaa4d32: rust-tests, mobile-checks,
desktop-tauri-checks, file-size-check, branch-skew.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Signed-off-by: Wes <wesbillman@users.noreply.github.com>
Co-authored-by: Carl <32a2e2c9d428ee08902cab75d956da2c1d235a22d4766b0dd4138bf6e2e5db1d@buzz.block.builderlab.xyz>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

deny.toml

@@ -15,6 +15,11 @@ ignore = [
     # remove these when upstream catches up.
     { id = "RUSTSEC-2026-0194", reason = "transitive via rust-s3 and mesh-llm→plist; trusted-input XML only; no upstream fix available yet" },
     { id = "RUSTSEC-2026-0195", reason = "transitive via rust-s3 and mesh-llm→plist; trusted-input XML only; no upstream fix available yet" },
+    # unsafe-libyaml 0.2.11 — unmaintained (repository archived 2024-03-25), not a
+    # vulnerability report. Transitive dep: serde_yaml → unsafe-libyaml. The serde_yaml_ng
+    # fork uses the same crate, so removing it means migrating YAML parsing in
+    # buzz-agent, buzz-persona, buzz-relay, buzz-workflow and desktop.
+    { id = "RUSTSEC-2024-0449", reason = "transitive via serde_yaml; unmaintained, not vulnerable; removal needs a YAML parser migration" },
 ]
 
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