arch: split ConfigRepository, extract polling, consolidate conversions, decouple protocol

- Value↔JSON: From impls on domain Value behind `json` feature, delete 4 duplicate converters
- ConfigRepository split into ConfigRepository (12), UserRepository (3), WidgetStateCache (2)
- polling orchestration moved from bootstrap to application::polling_service
- WidgetRenderer in client-domain owns scroll/cache, both clients use it
- network loop consolidated into client-application::run_connection_loop
- protocol crate drops domain dep, Wire↔Domain conversions move to adapters

crates/client-esp32/Cargo.lock

@@ -238,17 +238,13 @@ dependencies = [
  "client-domain",
  "domain",
  "embedded-graphics",
- "embedded-hal-bus",
- "embedded-text",
  "embuild",
  "esp-idf-hal",
  "esp-idf-svc",
  "esp-idf-sys",
  "log",
  "mipidsi",
- "postcard",
  "protocol",
- "serde",
 ]
 
 [[package]]
@@ -489,16 +485,6 @@ dependencies = [
  "embedded-hal 1.0.0",
 ]
 
-[[package]]
-name = "embedded-hal-bus"
-version = "0.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "513e0b3a8fb7d3013a8ae17a834283f170deaf7d0eeab0a7c1a36ad4dd356d22"
-dependencies = [
- "critical-section",
- "embedded-hal 1.0.0",
-]
-
 [[package]]
 name = "embedded-hal-nb"
 version = "1.0.0"
@@ -561,17 +547,6 @@ dependencies = [
  "strum 0.27.2",
 ]
 
-[[package]]
-name = "embedded-text"
-version = "0.7.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6cf5c72c52db2f7dbe4a9c1ed81cd21301e8d66311b194fa41c04fb4f71843ba"
-dependencies = [
- "az",
- "embedded-graphics",
- "object-chain",
-]
-
 [[package]]
 name = "embuild"
 version = "0.33.1"
@@ -1126,12 +1101,6 @@ dependencies = [
  "syn 2.0.118",
 ]
 
-[[package]]
-name = "object-chain"
-version = "0.1.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "41af26158b0f5530f7b79955006c2727cd23d0d8e7c3109dc316db0a919784dd"
-
 [[package]]
 name = "once_cell"
 version = "1.21.4"