fix(amr): improve unavailable model gating #14650

Job	Run time
Resolve runner profiles	10s
Static gate	12s
Detect validation scopes	13s
Validate Nix flake	3m 32s
Windows tools-pack payload tests	2m 36s
E2E Vitest	2m 30s
Workspace unit tests	1m 44s
Web workspace tests	3m 20s
Preflight	3m 10s
UI P0 smoke	3m 36s
Docker image build	3m 26s
Playwright visual (settings-workspace)	2m 48s
Playwright visual (entry-navigation)	3m 37s
UI P0 (workspace-restoration)	3m 36s
UI P0 (entry-settings)	3m 36s
UI P0 (project-runtime)	3m 35s
UI P0 (project-workspace)	3m 35s
Playwright critical (${{ matrix.group }})	0s
Validate workspace	7s
Runtime summary	7s
	45m 30s

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