docs: help/README catch up with the UI (pill count, event preview, store saving)

The audit of the help and READMEs against the current UI found four stale
pill enumerations and five undocumented behaviours:

- The Simulator tab has had five pills since the BIP pill landed; the help
  (EN/RU) and both READMEs said "four" and omitted BIP.  All four now name it
  (the help links §8.10).
- Test-script help: the envelope action's source override (82/83), the event
  action's fields being a JSON object in the step editor, edits being written
  to the store as you change them (no Save button; an incomplete draft stays
  local), and the templates wording adjusted.
- Subscribed-events help: the form's "event data (hex)" preview and how to
  copy it into a raw envelope test step.
- SCP80 help: the counter probe's amber outcome (a security verdict after a
  counter rejection saves the value and warns).
- Cards help: the key table's "Counter" row aligns with the editor's
  "Counter (hex)" heading.

sw cache simple-v384 (help files are precached).

frontend/sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'simple-v383';
+const CACHE = 'simple-v384';
 const URLS = [
   'index.html',
   'help.html',