fix: add @ember/app-tsconfig to docs-app to unblock production deploy

[Copilot]

• Identify root cause: kolay's api-docs build plugin calls require.resolve('@ember/app-tsconfig/tsconfig.json') — the package is only a devDependency of kolay, not installed when kolay is used as a dependency
• Add @ember/app-tsconfig: "^2.0.0" to docs-app/package.json devDependencies
• Update pnpm-lock.yaml with the resolved @ember/app-tsconfig@2.0.0 entry
• Verify CI passes

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[NullVoxPopuli]

@copilot ci errored

[Copilot]

@copilot ci errored

The install step was failing with ERR_PNPM_OUTDATED_LOCKFILE because I had updated docs-app/package.json without also updating pnpm-lock.yaml. Fixed in 649c497 — the lockfile now includes @ember/app-tsconfig@2.0.0.