v3.4.0: Clearance and Agent Hub as manila folders

Clearance

•	The three choices (Agent, Friendly, A-Cell) are aged manila folders lying fanned on the black page. Each one is tilted, with a sheet sticking out and a taped-on handwritten label in blue, black or red ink.
•	One mark on each folder: a paper clip and the worn green triangle on Agent, a coffee ring on Friendly, an EYES ONLY stamp on A-Cell.
•	Friendly now reads "A ready-made Agent for one night at the opera."
•	On a phone the folders stack one under another.

Agent Hub

•	The flat tabs are now a stack of aged manila folders. Each tab steps left, middle, right (left, right on a phone), with the name handwritten and the code typed. The open Agent's folder stands at the front.
•	Up to six Agents stand in the stack at any width. Past six, the strip is + New Recruit, Agents (N) ▾ and the open Agent. The menu is no longer phone-only.
•	The Agent File itself is unchanged. A-Cell keeps its flat tabs.

Frontend only: no backend, rules or Cloud Functions change.