feat: ServiceClient trait, HttpTransport, and SunbeamClient factory

Foundation layer for unified service client wrappers:
- AuthMethod enum (None, Bearer, Header, Token)
- ServiceClient trait with service_name(), base_url(), from_parts()
- HttpTransport with json(), json_opt(), send(), bytes() helpers
- SunbeamClient lazy factory with OnceLock-cached per-service clients
- Feature flags for all service modules (identity, gitea, matrix, etc.)

Bump: sunbeam-sdk v0.2.0

Cargo.lock

@@ -185,6 +185,16 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "assert-json-diff"
+version = "2.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "47e4f2b81832e72834d7518d8487a0396a28cc408186a2e8854c0f98011faf12"
+dependencies = [
+ "serde",
+ "serde_json",
+]
+
 [[package]]
 name = "async-broadcast"
 version = "0.7.2"
@@ -683,6 +693,24 @@ version = "2.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d7a1e2f27636f116493b8b860f5546edb47c8d8f8ea73e1d2a20be88e28d1fea"
 
+[[package]]
+name = "deadpool"
+version = "0.12.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0be2b1d1d6ec8d846f05e137292d0b89133caf95ef33695424c09568bdd39b1b"
+dependencies = [
+ "deadpool-runtime",
+ "lazy_static",
+ "num_cpus",
+ "tokio",
+]
+
+[[package]]
+name = "deadpool-runtime"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "092966b41edc516079bdf31ec78a2e0588d1d0c08f78b91d8307215928642b2b"
+
 [[package]]
 name = "delegate"
 version = "0.13.5"
@@ -1413,6 +1441,7 @@ dependencies = [
  "http",
  "http-body",
  "httparse",
+ "httpdate",
  "itoa",
  "pin-project-lite",
  "pin-utils",
@@ -3562,9 +3591,10 @@ dependencies = [
 
 [[package]]
 name = "sunbeam-sdk"
-version = "0.1.0"
+version = "0.2.0"
 dependencies = [
  "base64",
+ "bytes",
  "chrono",
  "clap",
  "dirs",
@@ -3592,6 +3622,7 @@ dependencies = [
  "tokio",
  "tokio-stream",
  "tracing",
+ "wiremock",
 ]
 
 [[package]]
@@ -4641,6 +4672,29 @@ version = "0.53.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d6bbff5f0aada427a1e5a6da5f1f98158182f26556f345ac9e04d36d0ebed650"
 
+[[package]]
+name = "wiremock"
+version = "0.6.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "08db1edfb05d9b3c1542e521aea074442088292f00b5f28e435c714a98f85031"
+dependencies = [
+ "assert-json-diff",
+ "base64",
+ "deadpool",
+ "futures",
+ "http",
+ "http-body-util",
+ "hyper",
+ "hyper-util",
+ "log",
+ "once_cell",
+ "regex",
+ "serde",
+ "serde_json",
+ "tokio",
+ "url",
+]
+
 [[package]]
 name = "wit-bindgen"
 version = "0.51.0"