feat(FN-2406): persist dashboard auth token and harden TUI layout

- Persist dashboard auth token in global settings and add daemon-token utilities for reuse
- Update dashboard CLI command auth precedence and token handling behavior
- Harden dashboard TUI log viewport budgeting to avoid footer overlap under constrained heights
- Expand CLI and TUI test coverage for token persistence, auth precedence, and environment mocking
- Refresh README/CLI/getting-started docs and add changesets for token persistence and TUI fix

packages/core/src/daemon-token.ts

@@ -64,6 +64,30 @@ export class DaemonTokenManager {
     return settings.daemonToken;
   }
 
+  /**
+   * Retrieve the existing daemon token or create/persist one if missing.
+   *
+   * Safe for concurrent callers: if another process writes the token between
+   * the initial read and generateToken(), this method re-reads and returns the
+   * persisted token instead of failing.
+   */
+  async getOrCreateToken(): Promise<string> {
+    const existing = await this.getToken();
+    if (existing) {
+      return existing;
+    }
+
+    try {
+      return await this.generateToken();
+    } catch (error) {
+      const afterRace = await this.getToken();
+      if (afterRace) {
+        return afterRace;
+      }
+      throw error;
+    }
+  }
+
   /**
    * Validate that a provided token matches the stored token.
    *