ui: gate controls by server/card state; move Custom files to Profiler

Availability model: server-down / server-up-no-card / card-equipped.
- header shows a symbolic indicator dot (red/yellow/green, tooltip)
- a 5s probe tracks /api/version+/api/status while not fully ready; the
  2s status poll takes over once connected
- controls declare data-needs='server' or 'card'; disabled + tooltip when
  the state does not satisfy them: equip (server), status/reset, file
  manager read/save/edit, raw APDU, profile-from-card, new snapshot,
  profiler list Check card, event Send, RAM install/explore delete,
  STK menu, Send STATUS, Verify vs pySim (server), pySim execute (server),
  PLI save/poll toggle (server)
- pysimConnect no longer conflates server and card: it records both and
  Connect stays usable without a card
- ramSendOta/ramInstallCap now use pysimFetch instead of raw fetch
  (relative /api URLs broke custom server URLs)

Custom files moved from the Card reader sub-tabs to the Profiler list
tabs (Profiles / Card snapshots / Custom files); help/README/AGENTS
updated. Tests: availability gating, indicator structure, moved tab.
SW cache v103 -> v104.

frontend/sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'otaman-v103';
+const CACHE = 'otaman-v104';
 const URLS = [
   'index.html',
   'help.html',