frontend: add HTTP OTA constructor (GP RAM-over-HTTP v1.1)

New 'HTTP OTA' sub-tab in the C-APDU constructor builds Remote Application
Management over HTTP payloads (GPC v2.2 Amendment B v1.1 §4.7):

- Trigger (Push SMS): 81 > 83 > 84/[85]/[86]/89, with optional Command
  Scripting template ('AA') wrap per TS 102 226 §5.2.1
- Store (SD admin params): STORE DATA TLV mode (80 E2 90 00), tag 85/A5
- Connection parameters: OPEN CHANNEL comprehension-TLV row editor + presets
  (Device Identities 02, Alpha 80, Bearer 01)
- Security parameters (Table 4-6): LV PSK Identity + LV KVN/KID
- Retry policy (Table 4-7): retry counter + TS 102 223 timer TLV (25 03)
- HTTP POST (Tables 4-8/9/10): 8A host / 8B agent / 8C URI, text→octets
- 'Pack into Secured packet' reuses packToSp for SPI/counter filling

Pure builder functions covered by 12 new tests reproducing the byte layout
from the spec tables. i18n entries, help.html/help-ru.html §2.7 added.
SW cache bumped otaman-v49 → v50.

frontend/sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'otaman-v49';
+const CACHE = 'otaman-v50';
 const URLS = [
   'index.html',
   'help.html',