scp81: always reuse the connection, collapsible options, label polish (v2.2.15)

- Keep-alive is no longer a setting: the TLS connection stays open between
  POSTs for the whole dialog (the card, as HTTP client, may still dial a new
  one at any time - GP Am. B 4.3.1) and only the 204 ends it, with a clean
  close_notify while the response is still buffered, then FIN. Dropped
  keep_alive/on_before_close/_scp81_wait_drained and the Connection-header
  'close' value (the API, status and UI no longer carry a keep-alive knob).
- The Listener Options block is a collapsed <details> with a 'custom' badge
  when anything differs from the reference defaults; the Reset button moved
  into the body so it cannot toggle the panel.
- X-Admin-Targeted-Application is opt-in (checkbox + //aid/... field, field
  disabled while off); X-Admin-Next-URI has a checkbox + hint explaining the
  one-shot rule of GP Am. B 4.4.2; both dependent fields grey out when
  unchecked.
- Labels/i18n: 'Chunked body (Transfer-Encoding: chunked)' stays English,
  'Show link events (...)', 'Теги comprehension-required'; the compact-header
  wording now spells out that it omits the optional space after ':' (legal
  per RFC 7230 3.2 OWS; saves one byte per header).
- Tests: a 200 keeps the socket for the next POST; the 204 closes with a
  mutual close_notify exchange; options helper/badge unit tests; removed the
  close-per-response and drain-wait tests. SW cache otaman-v181.

README.md

@@ -597,7 +597,7 @@ The **Listener** starts/stops the target the card's BIP channel is redirected to
 - **Pass-through (card destination)** — no listener and no target: the terminal connects each BIP channel to the destination the card requests in OPEN CHANNEL (`Other address` + transport port, TCP client remote only; no spec default port, so an incomplete request fails the channel). TLS is terminated by that platform, so the server's network is used (lab only).
 - **Capture (dump)** — accepts the card's TCP channel and logs whatever it sends (e.g. the TLS ClientHello) without answering.
 
-The **Options** block (applied at **Start**, remembered in the browser) exposes the HTTP framing (chunked body / chunk size, 0 = one TLS record / keep-alive / Connection header / compact headers / Next-URI), the script framing (indefinite `AE 80 …` or definite `AA` Command Scripting template, comprehension-required tags, targeted application) and link events (all modes, TS 102 223 §7.5.11). TLS has no settings: the listener offers TLS 1.0–1.2 and all PSK suites and lets the card negotiate; the log and state line report the version/cipher actually used, and a TLS/cipher handshake failure is logged as `tls-handshake-failed`.
+The **Options** block (collapsed by default; a `custom` marker appears when anything differs from the reference defaults; applied at **Start**, remembered in the browser) exposes the HTTP framing (Chunked body / chunk size, 0 = one TLS record / Connection header / compact headers, legal per RFC 7230 §3.2 / Next-URI checkbox + template, unchecked = one-shot), the script framing (indefinite `AE 80 …` or definite `AA` Command Scripting template, comprehension-required tags, optional `X-Admin-Targeted-Application` with its own checkbox) and **Show link events** (all modes, TS 102 223 §7.5.11). The connection stays open between POSTs and closes cleanly at the 204. TLS has no settings: the listener offers TLS 1.0–1.2 and all PSK suites and lets the card negotiate; the log and state line report the version/cipher actually used, and a TLS/cipher handshake failure is logged as `tls-handshake-failed`.
 
 **Script** selects the command list served over the session: **None** (leave the server's configured script) or one of the scripts created in the **Scripts** pill; **Restart script** re-queues the selected script with `force`, starting over from the first APDU.