fix: grant admin role to anonymous user and add DEFAULT_TOOL_VIEW env var

When AUTH_ENABLED=false, the anonymous user was assigned the "user" role
which lacks settings:write permission, making all settings saves return
403. Since no admin exists when auth is disabled, settings were
permanently read-only. Promote the anonymous user to "admin" so the
single user has full control of the instance.

Also adds DEFAULT_TOOL_VIEW env var (sidebar|fullscreen) following the
existing DEFAULT_THEME pattern, seeded via ensureDefaultSettings() on
first boot.

Closes #135

apps/api/src/lib/env.ts

@@ -27,6 +27,7 @@ const envSchema = z
     WORKSPACE_PATH: z.string().default("./tmp/workspace"),
     DEFAULT_THEME: z.enum(["light", "dark", "system"]).default("light"),
     DEFAULT_LOCALE: z.string().default("en"),
+    DEFAULT_TOOL_VIEW: z.enum(["sidebar", "fullscreen"]).default("sidebar"),
     CORS_ORIGIN: z.string().default(""),
     MAX_USERS: z.coerce.number().default(0),
     LOG_LEVEL: z.enum(["fatal", "error", "warn", "info", "debug", "trace"]).default("info"),