feat: SCP80 SMS concatenation + packet size / SMS count display (v3.2.0)

Packets longer than one SMS now go out as concatenated SMS-PP downloads
per TS 31.115 4.3 and the UI shows how many SMS a packet needs.

Server:
- `_split_secured_packet` cuts the command packet at the exact SMS
  user-data capacities (first SM 132 octets: concat IE 5 + CPI IE 2;
  following ones 134; a single-SM packet may be 137 with the CPI IE) and
  `_build_sms_tpdu` tags every segment with the fixed concatenation
  reference 01; `_build_sms_tpdu` also enforces the 140-octet budget.
- `_send_secured_packet` (shared by /api/send-ota and /api/ram-install)
  sends one ENVELOPE per segment in order, refuses more than
  MAX_ENVELOPE_SEGMENTS (5, the card's concatenation buffer) and reports
  `bytes`/`segments` in the response (RAM install per step as well).
- `_build_secured_packet`/`_encode_cmd_unlimited`: our own TS 102 225
  5.1.1 encoder on pySim's keyset/header constructors, byte-identical to
  pySim for packets <= 140 octets (tests) and not limited to one SMS
  (pySim refuses the longer ones, which is why they never went out).
- RAM LOAD blocks are no longer clamped to one SMS: 1-240 bytes of
  payload with the default 240 (the GP maximum); `load_block_size_auto`
  replaces `load_block_size_clamped`.

PWA:
- `scp80SegmentInfo` / `spSizeInfoText` show "N bytes . M SMS
  (concatenated)" under the packet field, turn red past 5 SMS and report
  size/SMS in the send result and the RAM step log; LOAD block hints and
  placeholders updated; EN/RU.

Tests/docs: Python +2 cases incl. segment order/capacities and byte
identity with pySim; Node drift guard against the server constants and
UI text tests; README/README_RUS, help EN/RU, docs/api.md, AGENTS.

README.md

@@ -431,6 +431,10 @@ PoR confirms the card received and executed the secured packet. Two modes:
 
 Delivery PoR (SPI2 `01`) is simpler — the card returns the PoR directly in the ENVELOPE response. Submit PoR (SPI2 `21`) is used when the card cannot respond inline (e.g. during ELF operations where the ENVELOPE response space is limited).
 
+#### SMS delivery
+
+A secured packet is delivered in an SMS-PP-DOWNLOAD ENVELOPE. Its size in bytes and the number of SMS it takes are shown under the packet field; a packet that does not fit one SMS is delivered as a **concatenated** SMS-PP download (TS 31.115 §4.3): the packet is split into SMS user-data parts (first SM 132 octets, following ones 134 — the first one additionally carries the concatenation and CPI information elements) and the segments are sent in order. A packet that would need more than 5 segments is refused — that is the practical limit of the card's concatenation buffer.
+
 #### References
 
 - ETSI TS 102 225 V18.1.0: Secured packet structure for UICC based applications
@@ -449,7 +453,7 @@ The RAM subtab offers two operations selected from the **Operation** dropdown:
 | Operation | Description |
 |---|---|
 | **Explore Card (all GP data)** | Queries GET STATUS for ISD, Applications, ELFs, and ELF Modules, plus GET DATA FF21 for memory info. Results appear in an explorer view with per-item **Delete** buttons. |
-| **Install Package (.cap file)** | Sends a `.cap` file to the card via the server: INSTALL\[for load\] → LOAD ×N → INSTALL\[for install (+make selectable)\]. |
+| **Install Package (.cap file)** | Sends a `.cap` file to the card via the server: INSTALL\[for load\] → LOAD ×N → INSTALL\[for install (+make selectable)\]. The load file is split into LOAD APDUs of 1–240 bytes of payload (240 by default, editable in **LOAD block size**); a secured packet larger than one SMS is delivered as a concatenated SMS-PP download of up to 5 segments. |
 
 #### Explorer View