EF.SST: tri-state editor (deleted / allocated-off / on)

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.)

frontend/help.html

@@ -408,7 +408,7 @@
 	<ul class="list-disc list-inside text-sm space-y-1 mb-3">
 		<li><strong>Read raw / Read decoded</strong> — read the selected file as a hex dump or as a decoded field table (client-side EF decoders: IMSI, ICCID, SPN, PLMN lists, LOCI/PSLOCI/EPSLOCI, ADN/MSISDN, service tables, SUME, …); the decoded table is built in the browser from the same raw bytes (no server-side decode). The highlighted pill is the current view; clicking either pill (re-)reads the file. <strong>Read decoded</strong> is disabled when the client-side decoders do not cover the file (name/FID check, before reading).</li>
 		<li><strong>Edit raw</strong> — edit the raw hex data, <strong>Save</strong> to write back (or <strong>Cancel</strong>); transparent files use a textarea, record files one input per record with selection checkboxes. <strong>Edit raw</strong> switches to the hex view first and reads the file if needed.</li>
-		<li><strong>Edit decoded</strong> — edit the file through its own decoded form, encoded in the browser and written with the normal update path. The encoders cover <strong>EF.SPN</strong>, <strong>EF.PNN</strong>, the PLMN lists (<strong>PLMNsel / FPLMN / EHPLMN</strong> and the access-technology lists <strong>PLMNwAcT / OPLMNwAcT / HPLMNwAcT</strong>), the dialling-number files (<strong>ADN / FDN / SDN / MSISDN / LND / BDN</strong>), the service tables (<strong>UST / IST / EST</strong>; <strong>SST</strong> stays read-only until the SIM allocated/activated editor exists), <strong>ACC</strong>, <strong>PHASE</strong>, <strong>HPPLMN</strong>, <strong>AD</strong>, <strong>ICCID / IMSI</strong> (behind a confirmation — writing them changes the card identity) the cell-broadcast lists (<strong>CBMI / CBMID / CBMIR</strong>) and <strong>EF.SMSP</strong> (the full SMS-parameter form: alpha, TP-DA and TS-SCA with their addressing rules and TON, TP-PID, TP-DCS and the relative TP-VP, each with an <em>absent (the ME default applies)</em> toggle and live DCS/validity hints). A transparent file gets one form (SPN fields, PLMN rows with add/remove, PNN items with add/remove); a record file gets one form per record with a selection checkbox that is auto-checked when a field changes, so only the edited records are written. <strong>Save</strong> validates every selected record before writing anything; files without an encoder keep the button disabled with a tooltip. Extension pointers (EF.EXT1–EF.EXT5) and the BDN comparison-method byte are preserved, and editing a number that continues in an extension file is refused.</li>
+		<li><strong>Edit decoded</strong> — edit the file through its own decoded form, encoded in the browser and written with the normal update path. The encoders cover <strong>EF.SPN</strong>, <strong>EF.PNN</strong>, the PLMN lists (<strong>PLMNsel / FPLMN / EHPLMN</strong> and the access-technology lists <strong>PLMNwAcT / OPLMNwAcT / HPLMNwAcT</strong>), the dialling-number files (<strong>ADN / FDN / SDN / MSISDN / LND / BDN</strong>), the service tables (<strong>UST / IST / EST</strong> and <strong>SST</strong> — the SIM table, edited per service as deleted / allocated-off / on), <strong>ACC</strong>, <strong>PHASE</strong>, <strong>HPPLMN</strong>, <strong>AD</strong>, <strong>ICCID / IMSI</strong> (behind a confirmation — writing them changes the card identity) the cell-broadcast lists (<strong>CBMI / CBMID / CBMIR</strong>) and <strong>EF.SMSP</strong> (the full SMS-parameter form: alpha, TP-DA and TS-SCA with their addressing rules and TON, TP-PID, TP-DCS and the relative TP-VP, each with an <em>absent (the ME default applies)</em> toggle and live DCS/validity hints). A transparent file gets one form (SPN fields, PLMN rows with add/remove, PNN items with add/remove); a record file gets one form per record with a selection checkbox that is auto-checked when a field changes, so only the edited records are written. <strong>Save</strong> validates every selected record before writing anything; files without an encoder keep the button disabled with a tooltip. Extension pointers (EF.EXT1–EF.EXT5) and the BDN comparison-method byte are preserved, and editing a number that continues in an extension file is refused.</li>
 		<li><strong>Probe all files</strong> — walks the whole tree (including custom files) and marks every entry present (normal) or absent (red ✗, no expand arrow); empty-but-present DFs show <code class="font-mono text-sm">(empty)</code>. Shows progress <em>N / total</em>, can be stopped, and finishes with a present/absent summary. Files are only verified when expanded or probed — browsing stays lazy.</li>
 		<li><strong>ADM</strong> — files that need the administrator PIN fail with <code class="font-mono text-sm">6982</code>/<code class="font-mono text-sm">9804</code>; if the matching card preset (same ICCID) carries an ADM key, a <strong>Verify ADM</strong> button appears next to the error and the header badge (<code class="font-mono text-sm">ADM ✓/✗ ⚿</code>) becomes clickable. Every wrong key consumes an attempt: the remaining attempts are shown and a retry asks for confirmation. A blocked ADM cannot be recovered here — it needs the card&rsquo;s unblock key.</li>
 	</ul>