test(cli): bare-metal end-to-end integration test

Spawns the pre-built `picloud` binary against DATABASE_URL on a
private port, logs in over HTTP to mint a bearer token, then drives
`pic` through the full edit-deploy-invoke-tail loop with a unique
app slug per run and a `Drop`-based cleanup. Gated on DATABASE_URL
and tagged `#[ignore]` to match the existing integration-test
pattern in `crates/picloud/tests/api.rs`.

The test uses the dev `admin/admin` credentials (overridable via
PICLOUD_CLI_E2E_USERNAME / _PASSWORD) because the bootstrap env
vars are inert once the DB has any admin row.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/picloud-cli/tests/fixtures/hello.rhai

@@ -0,0 +1,4 @@
+// Smallest possible Rhai script for the integration test: returns a JSON
+// object so the orchestrator wraps it as the HTTP response body.
+let body = #{ ok: true, greeting: "hello from pic" };
+body