v3.22.0: the event action uses the Simulator's forms (all modelled events)

The test-script event action edited its fields as a JSON textarea and only
accepted the four events events.py builds; every other event needed the raw
envelope action with hand-copied hex.  It now renders the same EVENT_FORMS
form the Phone tab's send dialog uses, for every modelled event (29; no
release gating - a script may target another card).

- PWA: the field renderer/collector is shared (eventFormFieldsHtml /
  eventFormValues / eventFormPatternError / eventFormSrc / eventFieldGroupsUpdate);
  the Phone tab keeps its ids, its release gating and its onchange updaters,
  the step editor uses test-f-ev- ids, the generic group updater and a live
  Event data (hex) preview with the one-ENVELOPE check.  The event select
  lists all EVENT_FORMS events (the numeric keys are decimal strings -
  parseInt(k, 10)); the action stores the collected fields, the built data
  and the event's source (fixed cfg.src or the cfg.srcField input - the
  action never carried src before, so MT call / IMS registration / slices
  could not be network-sourced).  The JSON textarea is gone.
- engine: the `event` action keeps `fields` validation for the four
  server-built events (a stray data hex is ignored) and accepts the
  form-built `data` for every other event - hex-validated and checked
  against events.EVENT_DATA_MAX (244, the one-ENVELOPE budget; server.py's
  _EVENT_DATA_MAX now reads it from events.py).  The runner builds the four
  at run time (fresh host clock) and sends the stored data for the rest.
- tests: the engine's data path (accepted / missing / malformed / oversized,
  the four still fields-built), the runner sending the data (fake scc), the
  editor's collect/prefill/patterns/source (Node), the shared helpers.
  Docs: test-scripts.md, api.md, help EN/RU.  Tests: 838 frontend +
  797 Python; sw cache simple-v401.

pysim_simple_server/events.py

@@ -30,6 +30,12 @@ EVENT_ACCESS_TECH = 0x0B
 EVENT_NETWORK_REJECTION = 0x12
 EVENT_DATA_CONNECTION = 0x1D
 
+# The single-ENVELOPE budget of the event data (TS 102 223: the inner data is
+# capped at 252 bytes, 8 of them the event-list + device-identities header;
+# chained delivery is not implemented).  server.py's _EVENT_DATA_MAX and the
+# PWA's EVENT_INNER_MAX mirror this value.
+EVENT_DATA_MAX = 244
+
 # The event code from a script's `event` value (a hex byte, or one of these
 # names - the PWA's display names and short keywords).
 EVENT_NAMES = {