v3.23.1: the PLI dictionary defaults and the PLI codec tag fixes

An unconfigured PLI dictionary answered result-ok with no data object,
which confuses applications that expect data.  The dictionary now has a
base layer of sensible defaults for the qualifiers the pinned ETSI specs
define (TS 102 223 8.x, tags per TS 101 220 V18.3.0 Table 7.23):

- location as the test network 001/01 + LAC 0000 (8.19),
- the classic test IMEI 490154203237518 as F-padded BCD (8.20) and its
  IMEISV (8.74),
- language 'en' (8.45), Timing Advance (2E/AE), E-UTRAN (8.61; UTRAN +
  E-UTRAN for the multiple-technology qualifier 0E),
- automatic search mode (8.75), a full battery (8.76).

An override set through /api/pli-dict wins, and clearing a field restores
its default (the PWA's Save re-renders the effective values; the GET returns
the override or the default for the full qualifier set).  The date/time
qualifier stays empty so the host clock keeps answering it; the
3GPP/3GPP2-specific qualifiers (NMR, ESN, MEID, CSG/HNB, WLAN, slices,
CAG, ...) stay empty - the ETSI specs define no contents for them, and a
fabricated object would mislead the application more than no answer.

Verifying the values against the pinned tag table exposed pre-existing bugs
in the PWA's PLI inline codecs, fixed here:
- Timing Advance used C6 (a 3GPP2 tag) -> 2E/AE;
- IMEISV used 94 (the IMEI tag) -> 62/E2;
- Network Search Mode used AD (the Language tag) -> 65/E5, and its labels
  were swapped ('00' Manual / '01' Automatic per 8.75);
- the battery field was a percentage where 8.76 is an enum ('00' very low
  ... '04' full, 'FE'/'FF');
- encImeiPli padded the odd 15th digit with 0 instead of F (TS 124 008).

Docs: help EN/RU, api.md, the guide.  Tests: the defaults + the resolution
order (Python), the HTTP endpoint's defaults/override/clearing, the codec
tags/labels and a server-defaults drift guard (Node).  846 frontend +
829 Python; sw cache simple-v414.

frontend/help.html

@@ -529,7 +529,7 @@
 		<li><strong>06</strong> Access Technology &middot; <strong>08</strong> IMEISV &middot; <strong>09</strong> Search Mode</li>
 		<li><strong>0A</strong> Battery &middot; <strong>0E</strong> Multiple Access Technologies</li>
 	</ul>
-	<p class="text-sm mb-3">Values persist server-side until restart. When the card issues PLI, the server injects the dictionary values into the TERMINAL RESPONSE - also into a test-script expectation's answer.</p>
+	<p class="text-sm mb-3">Values persist server-side until restart.  Sensible defaults are pre-settled for the qualifiers the ETSI specs define (location as the test network 001/01, the test IMEI 490154203237518 and its IMEISV, language &lsquo;en&rsquo;, E-UTRAN access technology, automatic search mode, a full battery): a value you set overrides its default, and <strong>clearing the field restores it</strong>; the date/time qualifier is answered from the host clock while empty, and the 3GPP/3GPP2-specific qualifiers (NMR, ESN, MEID, CSG/HNB, WLAN, slices, CAG, &hellip;) stay empty - the ETSI specs define no contents for them.  When the card issues PLI, the server injects the values into the TERMINAL RESPONSE - also into a test-script expectation's answer.</p>
 
 	<h3 id="network-simulation" class="text-lg font-medium mb-2">8.7 Network simulation</h3>
 	<p class="text-sm mb-2">Replays the write patterns a real phone performs when the network condition changes (trace study in <code class="font-mono text-sm">projects/UICC_NAA.md</code>): EPS attach, service loss / limited service, roaming denial, 2G fallback, SMS delivery, cell-broadcast reconfiguration and AUTHENTICATE. One button per scenario; the card must be equipped.</p>