profiler: check a profile against a stored card snapshot

Each profile row gets a Check card snapshot button next to Check card.
It opens a picker listing the stored snapshots (name, ICCID, date, file
count) and runs the profile rules offline against the selected snapshot,
showing the usual report titled 'profile — snapshot'.

profilerRunRule() accepts an optional data source: profilerLiveSource()
(default) wraps /api/select + /api/read, profilerSnapshotSource() serves
select/read from the snapshot files. Contents missing from the snapshot
are reported as unverifiable errors ('Content not captured in snapshot')
rather than mismatches. The shared check loop moved into
profilerRunProfile().

Tests for the snapshot source and snapshot-based checks; help docs
updated; SW cache v84 -> v85.

frontend/help.html

@@ -371,7 +371,7 @@
 		<li><strong>New profile</strong> — creates an empty ruleset after prompting for a name.</li>
 		<li><strong>Profile from card</strong> — scans the equipped card and generates one rule per existing file (see below), then opens the editor.</li>
 		<li><strong>Import profile</strong> — loads a ruleset from a JSON file (the name is stored inside the JSON).</li>
-		<li>Each profile row shows its name and creation time, with <strong>Check card ▶</strong>, <strong>Edit</strong>, <strong>Export</strong> (download JSON), and <strong>Delete</strong> actions.</li>
+		<li>Each profile row shows its name and creation time, with <strong>Check card ▶</strong>, <strong>Check card snapshot</strong>, <strong>Edit</strong>, <strong>Export</strong> (download JSON), and <strong>Delete</strong> actions.</li>
 	</ul>
 	<h4 class="font-medium mb-1">Filesystem rules</h4>
 	<p class="text-sm mb-2">Rules run sequentially. The editor shows the symbolic pySim name (when known) next to each rule&rsquo;s path; use <strong>Add rule</strong> to append one and <strong>Save</strong> to keep the changes. A filesystem rule is defined by:</p>
@@ -391,6 +391,7 @@
 		<li><strong>New snapshot</strong> &mdash; asks for a name and scans the card, then returns to the list.</li>
 		<li><strong>Import snapshot</strong> &mdash; loads a snapshot from a JSON file.</li>
 		<li>Each snapshot row has <strong>Open</strong>, <strong>Export</strong>, and <strong>Delete</strong>. <strong>Open</strong> shows all captured data read-only (raw FCI with the decoded FCI, contents); only the snapshot name is editable.</li>
+		<li><strong>Check card snapshot</strong> on a profile row runs the profile rules against a snapshot you pick from the list, without a card reader. The report is the same as a live check; files whose contents were not captured during the scan are reported as unverifiable errors.</li>
 	</ul>
 
 <h3 id="usage-scenarios" class="text-lg font-medium mb-2">5.7 Usage scenarios</h3>