fix: robust equip-state detection and review follow-ups (v3.5.4)

Code-review follow-ups for v3.5.2/v3.5.1, plus a test flake found while
re-running the suites:

- F1: a half-initialized equip is no longer reported as success.  cmd2
  swallows exceptions raised inside the equip command (and prints no
  traceback by default), while PysimApp.equip() assigns card/rs before it
  registers the command sets - so app.card alone once let the "CommandSet ...
  is already installed" abort pass as done while /api/tree stayed broken.
  The auto-equip attempt now captures the output with cmd2 debug on (a
  swallowed error prints a traceback), requires the new profile's command-set
  instances to be installed (_app_equip_complete), and the manual
  /api/command equip branch applies the post-equip refresh only when that
  check passes (and reports it in the output when it does not).
- F3: SCARD_E_SHARING_VIOLATION is recoverable (a rebuild cannot free another
  process's claim) instead of transport-fatal.
- F4: SPI1 b2b1 = 11 (Digital Signature) is refused instead of building an
  unsigned packet; help notes RC is CRC-32 only (KID CRC-16 not offered).
- F5: _clear_app_card_state removes the muted stdout again when the app object
  had no stdout attribute.
- F7: the watchdog re-arm keeps its rate-limit window when the trigger is
  busy/disabled instead of consuming it.
- F2: stale docstring in _auto_equip_attempt.
- tests: equip-state units, half-equip and captured-traceback failures,
  unequip-on-failure, busy trigger, sharing violation, DS refusal.
- bonus: the MCC/MNC random-pick test could fail because a dict keyed by
  (mcc, mnc) keeps one of two entries (the bundled list carries both a real
  and an MVNO entry for 234/18 and 234/28); the picker was correct - the
  assertion now checks the pair against the non-MVNO pairs.

549 frontend / 421 Python green; version 3.5.4; sw cache simple-v256.

frontend/sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'simple-v255';
+const CACHE = 'simple-v256';
 const URLS = [
   'index.html',
   'help.html',