fix(simulate): offer lk cloud auth when no project is linked

[u9g]

Problem

On a fresh install with no project linked, lk agent simulate text (the dashboard's getting-started command) exits 1 with only:

api-key is required

Nothing tells the user to run lk cloud auth. This failure happens on the client before any request reaches the server, so server-side telemetry never records it. Other agent commands like lk agent create and lk agent deploy instead offer to authenticate.

The cause: loadSimulateProject resolved credentials with loadProjectDetails, which has no fallback when nothing resolves. The other agent commands go through requireProject, which does.

Fix

loadSimulateProject now resolves through requireProject. Affected commands: simulate text, audio, view and export.

Situation	Before	After
Terminal, no project linked	api-key is required	"No local projects found. Authenticate one?" prompt, which runs the lk cloud auth flow and continues with the new project
Non-interactive (CI, piped), no project	api-key is required	no projects configured; run 'lk cloud auth' in an interactive terminal or set --project
Several projects linked, none default	api-key is required	Project picker

Anything that already resolved still resolves the same way: --project, env/flag credentials, livekit.toml, and the default project. --experimental-auth is still rejected, by the same experimentalAuthGate.

Verification

• go test ./cmd/lk/ passes.
• Ran in agent-starter-python with an empty HOME, comparing main with this branch:
  • TTY: main prints api-key is required. This branch shows the authenticate prompt, and Enter starts the lk cloud auth device flow.
  • Non-TTY: this branch prints the lk cloud auth / --project message.
  • LIVEKIT_URL/LIVEKIT_API_KEY/LIVEKIT_API_SECRET env: unchanged. It prints "Using url, api-key, api-secret from environment" and starts the agent with no prompt.

[u9g]

On a fresh install with no linked project: main prints a bare api-key is required, this branch prompts to authenticate with lk cloud auth, and a non-interactive run says to run lk cloud auth or set --project.

sim-auth-prompt.mp4