feat: real XMP sidecar adapter, replaces LogSidecarWriter stubs

- adapters-sidecar: XmpSidecarWriter using xmp_toolkit
- Writes StructuredData → XMP with EXIF/DC/XMP namespace routing
- Reads XMP back to StructuredData
- Wired into bootstrap + worker, deleted both LogSidecarWriter stubs

Cargo.lock

@@ -78,6 +78,17 @@ dependencies = [
  "uuid",
 ]
 
+[[package]]
+name = "adapters-sidecar"
+version = "0.1.0"
+dependencies = [
+ "async-trait",
+ "domain",
+ "tokio",
+ "tracing",
+ "xmp_toolkit",
+]
+
 [[package]]
 name = "adapters-storage"
 version = "0.1.0"
@@ -478,6 +489,7 @@ dependencies = [
  "adapters-event-transport",
  "adapters-nats",
  "adapters-postgres",
+ "adapters-sidecar",
  "adapters-storage",
  "anyhow",
  "application",
@@ -988,6 +1000,12 @@ dependencies = [
  "percent-encoding",
 ]
 
+[[package]]
+name = "fs_extra"
+version = "1.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "42703706b716c37f96a77aea830392ad231f44c9e9a67872fa5548707e11b11c"
+
 [[package]]
 name = "futures"
 version = "0.3.32"
@@ -2020,6 +2038,28 @@ dependencies = [
  "libm",
 ]
 
+[[package]]
+name = "num_enum"
+version = "0.7.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5d0bca838442ec211fa11de3a8b0e0e8f3a4522575b5c4c06ed722e005036f26"
+dependencies = [
+ "num_enum_derive",
+ "rustversion",
+]
+
+[[package]]
+name = "num_enum_derive"
+version = "0.7.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "680998035259dcfcafe653688bf2aa6d3e2dc05e98be6ab46afb089dc84f1df8"
+dependencies = [
+ "proc-macro-crate",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "object_store"
 version = "0.11.2"
@@ -2261,6 +2301,15 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "proc-macro-crate"
+version = "3.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e67ba7e9b2b56446f1d419b1d807906278ffa1a658a8a5d8a39dcb1f5a78614f"
+dependencies = [
+ "toml_edit",
+]
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.104"
@@ -3474,6 +3523,36 @@ dependencies = [
  "webpki-roots 0.26.11",
 ]
 
+[[package]]
+name = "toml_datetime"
+version = "1.1.1+spec-1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3165f65f62e28e0115a00b2ebdd37eb6f3b641855f9d636d3cd4103767159ad7"
+dependencies = [
+ "serde_core",
+]
+
+[[package]]
+name = "toml_edit"
+version = "0.25.12+spec-1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d2153edc6955a6c354fad8f5efd38b6a8769bdccf9fe50f8e1329f81b0baa5d7"
+dependencies = [
+ "indexmap",
+ "toml_datetime",
+ "toml_parser",
+ "winnow",
+]
+
+[[package]]
+name = "toml_parser"
+version = "1.1.2+spec-1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a2abe9b86193656635d2411dc43050282ca48aa31c2451210f4202550afb7526"
+dependencies = [
+ "winnow",
+]
+
 [[package]]
 name = "tower"
 version = "0.5.3"
@@ -4164,6 +4243,15 @@ version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
 
+[[package]]
+name = "winnow"
+version = "1.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0592e1c9d151f854e6fd382574c3a0855250e1d9b2f99d9281c6e6391af352f1"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "wit-bindgen"
 version = "0.46.0"
@@ -4266,6 +4354,7 @@ dependencies = [
  "adapters-exif",
  "adapters-nats",
  "adapters-postgres",
+ "adapters-sidecar",
  "adapters-storage",
  "adapters-thumbnail",
  "anyhow",
@@ -4286,6 +4375,18 @@ version = "0.6.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1ffae5123b2d3fc086436f8834ae3ab053a283cfac8fe0a0b8eaae044768a4c4"
 
+[[package]]
+name = "xmp_toolkit"
+version = "1.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "04517ad6f440d16e52ade0ad6d781029313bdacaac4590de9a9114f8d737af61"
+dependencies = [
+ "cc",
+ "fs_extra",
+ "num_enum",
+ "thiserror",
+]
+
 [[package]]
 name = "y4m"
 version = "0.8.0"