Give EF.SST its own per-file editor for the 2-bit SIM service table
(TS 51.011 10.3.7: allocated + activated per service):
- efEncSst encodes the pair layout, preserving unmodelled pairs and the
file length; validates service number, fit and state.
- A new `bits2` field kind renders a three-state select per service and
collects {n, name, allocated, activated}; registered as EF_SST_FIELDS
with the encoder (df '7F20'), and SST leaves EF_READONLY_NAMES.
- i18n: Deleted/Off/On + the state-error and hint strings (EN/RU).
Docs/help updated: SST is no longer read-only. Frontend 1093 + Python
1090 tests green. (Version/sw bump still deferred for the unreleased
decoded-editing batch.)