feat(http): enable gzip + brotli decompression for reqwest clients (#704)

* feat(http): enable gzip + brotli decompression for reqwest clients

All Rust-side HTTP clients now advertise Accept-Encoding and transparently
decode compressed responses. reqwest auto-decompresses by default once the
features are enabled, so this is a pure dependency-feature change with no
call-site edits.

Added to all five reqwest declarations across the Cargo workspace
(top psysonic crate + psysonic-audio / -analysis / -integration / -syncfs).
The real wire savings land on JSON payloads — Navidrome native /api,
Bandsintown, Radio-Browser, Last.fm — measured at roughly -76% to -93% on
earlier curl tests. Crates that only fetch already-compressed audio bytes
get the features too for consistency: reqwest just advertises the header
there, so there's no runtime cost when the server returns data as-is.

Cargo.lock grows additively (async-compression + compression codecs); no
other crates moved.

* docs(changelog): add entry for HTTP gzip + brotli (#704)

src-tauri/Cargo.lock

@@ -128,6 +128,18 @@ dependencies = [
  "pin-project-lite",
 ]
 
+[[package]]
+name = "async-compression"
+version = "0.4.42"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e79b3f8a79cccc2898f31920fc69f304859b3bd567490f75ebf51ae1c792a9ac"
+dependencies = [
+ "compression-codecs",
+ "compression-core",
+ "pin-project-lite",
+ "tokio",
+]
+
 [[package]]
 name = "async-executor"
 version = "1.14.0"
@@ -671,6 +683,24 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "compression-codecs"
+version = "0.4.38"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ce2548391e9c1929c21bf6aa2680af86fe4c1b33e6cea9ac1cfeec0bd11218cf"
+dependencies = [
+ "brotli",
+ "compression-core",
+ "flate2",
+ "memchr",
+]
+
+[[package]]
+name = "compression-core"
+version = "0.4.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cc14f565cf027a105f7a44ccf9e5b424348421a1d8952a8fc9d499d313107789"
+
 [[package]]
 name = "concurrent-queue"
 version = "2.5.0"
@@ -5950,13 +5980,18 @@ version = "0.6.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d4e6559d53cc268e5031cd8429d05415bc4cb4aefc4aa5d6cc35fbf5b924a1f8"
 dependencies = [
+ "async-compression",
  "bitflags 2.11.1",
  "bytes",
+ "futures-core",
  "futures-util",
  "http",
  "http-body",
+ "http-body-util",
  "iri-string",
  "pin-project-lite",
+ "tokio",
+ "tokio-util",
  "tower",
  "tower-layer",
  "tower-service",