feat(call-home): Implement Auto Call Home configuration management

- Added `CallHomeConfig` model to represent the Auto Call Home settings.
- Introduced methods in `MiniMateClient` for reading (`get_call_home_config`) and writing (`set_call_home_config`) the call home configuration.
- Updated `MiniMateProtocol` with new commands for call home operations (SUB 0x2C for read, SUB 0x7E for write, and SUB 0x7F for confirm).
- Created API endpoints for retrieving and updating call home settings in the server.
- Enhanced the web interface with a new "Call Home" tab for user interaction with call home settings.
- Implemented JavaScript functions for reading and writing call home configurations from the web app.

CHANGELOG.md

@@ -4,6 +4,57 @@ All notable changes to seismo-relay are documented here.
 
 ---
 
+## v0.12.3 — 2026-04-20
+
+### Added
+
+- **Auto Call Home config protocol** — Full read/write/decode/encode pipeline for the
+  device's Remote Access → Setup Unit ACH settings, confirmed from 4-20-26 call home
+  settings captures.
+
+  **Protocol (new):**
+  - `SUB 0x2C` — Call Home Config READ (response `0xD3`); two-step read; data offset
+    `0x7C` = 124; raw payload 125 bytes (1-byte longer than DATA_LENGTH due to DLE-escaped
+    `\x10\x03` at raw[117:119] representing num_retries = 3)
+  - `SUB 0x7E` — Call Home Config WRITE (response `0x81`); 127-byte payload (125-byte read
+    payload + `\x00\x00`); offset = `data[1]+2 = 0x7E`; write format (DLE-aware checksum)
+  - `SUB 0x7F` — Call Home WRITE CONFIRM (response `0x80`); no data
+
+  **Field map (confirmed from 10-frame BW TX diff):**
+  - `raw[5]` — auto_call_home_enabled (bool)
+  - `raw[6:46]` — dial_string (40-byte null-padded ASCII)
+  - `raw[87]` — after_event_recorded (bool)
+  - `raw[91]` — at_specified_times (bool)
+  - `raw[93]` — time1_enabled / `raw[101]` — time1_hour / `raw[102]` — time1_min
+  - `raw[95]` — time2_enabled / `raw[105]` — time2_hour / `raw[106]` — time2_min
+  - `raw[117:119]` — `\x10\x03` (DLE-escaped 0x03 = num_retries value 3)
+  - `raw[120]` — time_between_retries_sec / `raw[122]` — wait_for_connection_sec / `raw[124]` — warm_up_time_sec
+
+  **Library (`minimateplus/`):**
+  - `models.py` — `CallHomeConfig` dataclass (14 fields; `raw` bytes preserved for
+    round-trip writes)
+  - `protocol.py` — `SUB_CALL_HOME = 0x2C`, `SUB_CALL_HOME_WRITE = 0x7E`,
+    `SUB_CALL_HOME_CONFIRM = 0x7F`; `read_call_home_config()`, `write_call_home_config()`
+  - `client.py` — `get_call_home_config()`, `set_call_home_config()`,
+    `_decode_call_home_config()` (handles DLE prefix at raw[117]),
+    `_encode_call_home_config()` (patches in-place; raises `ValueError` if hour/min = 3)
+
+  **REST API (`sfm/server.py`):**
+  - `GET /device/call_home` — reads and decodes call home config from device
+  - `POST /device/call_home` — reads, patches specified fields, writes back to device
+  - `CallHomeConfigBody` Pydantic model with 9 optional writable fields
+
+  **Web UI (`sfm/sfm_webapp.html`):**
+  - New "Call Home" tab with enable flag, dial string (read-only), after-event trigger,
+    at-specified-times flag, two time slots (enable + HH:MM each), and read-only retry
+    settings (num_retries, time_between_retries_sec, wait_for_connection_sec,
+    warm_up_time_sec)
+  - "Read from Device", "Write to Device", "Clear Form" action buttons
+  - Client-side guard: rejects hour or minute value equal to 3 with a clear message
+    explaining the DLE-encoding limitation
+
+---
+
 ## v0.12.2 — 2026-04-20
 
 ### Added / Fixed