feat: polling on by default and an effective-state toggle (v3.5.10)

- Background STATUS polling is enabled by default, per the spec's idle
  polling rule (TS 102 221 14.6.2): `_POLL_ENABLED = True`, __main__ runs
  `_poll_enable()` regardless of card presence (--poll-interval 0 still
  disables) and `_do_status_poll` keeps ticking while enabled even without
  a session, so a cardless start resumes as soon as a card appears.
- A new card session clears a POLLING OFF from the previous card in
  `_apply_equipped_card` before re-enabling polling.
- The Phone-tab toggle now shows the *effective* state: OFF in amber
  ("card disabled polling (POLLING OFF)") while the card suspended
  proactive polling, back to ON on the next POLL INTERVAL.  The 5 s
  background poll now passes `card_disabled` through (it was dropped, so
  an autonomously received POLLING OFF never reached the UI).
- Tests: poll_ui updated (button OFF while suspended, warning path),
  test_poll +2 (cardless ticking, module default via a subprocess check).
- Help EN/RU, docs/api.md, AGENTS; version 3.5.10; sw cache simple-v263.

573 frontend / 441 Python green.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "pysim-simple-server"
-version = "3.5.9"
+version = "3.5.10"
 description = "HTTP REST server wrapping pysim for the SIMple PWA"
 requires-python = ">=3.8"
 # pysim is a git-only dependency installed explicitly by setup.bat/setup.sh.