ui: gate Read decoded on client-side decoder availability (v2.7.10)

Files without a client-side decoder used to fall back to a raw view when
the Decoded pill was pressed.  The decoder is resolved by name/FID
(efFindDecoder) before any read, so the pill can be disabled instead.

- pysimFsHasDecoder() mirrors the decoded view's resolution (tree node
  name, FID fallback).
- pysimApplyAvailability() honours a new data-needs-decoder marker:
  disabled with the existing 'No decoder for this file' tooltip; the
  card hint still wins when no card is equipped.
- pysimFsClickFile() re-runs the availability pass after selecting a
  file; pysimFsSetMode('dec') ignores the call without a decoder.
- tests: indicator (enable/disable/tooltip precedence), fs_edit
  (decoded guard, name/FID resolution); help EN/RU.

frontend/help.html

@@ -352,7 +352,7 @@
 	<h3 id="file-manager" class="text-lg font-medium mb-2">6.1 File manager</h3>
 	<p class="text-sm mb-2">The file system tree is displayed on the left; selecting a file opens its detail pane on the right. Entries are grouped with DFs above EFs and sorted by <strong>FID</strong> or symbolic <strong>Name</strong> (pills pinned above the scrolling tree together with <strong>Probe all files</strong>; the choice is remembered in <code class="font-mono text-sm">localStorage</code>). Selecting a file also shows its FID, file type, size / record layout and the decoded FCI above the content pane.</p>
 	<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 server-side pySim JSON of the same read stays available in the collapsed <em>pySim JSON (server)</em> disclosure. The highlighted pill is the current view; clicking either pill (re-)reads the file.</li>
+		<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 server-side pySim JSON of the same read stays available in the collapsed <em>pySim JSON (server)</em> disclosure. 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. The decoded view is read-only — <strong>Edit raw</strong> switches to the hex view first and reads the file if needed.</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>