feat(lite): vendor SDXL backend source; source deps from git.dragonx.is

Vendor the two local Rust crates that build the lite backend artifact into
third_party/silentdragonxlite/ (the qtlib C-ABI wrapper + the silentdragonxlitelib
core, with proto/res and all the lite-send fixes), and point
build-lite-backend-artifact.sh's default --backend-dir there, so the lite wallet
builds without the upstream SilentDragonXLite repo.

External build inputs are now only the Rust toolchain + git.dragonx.is + crates.io:
- the 6 librustzcash git deps point at the git.dragonx.is/DragonX/librustzcash
  mirror (pinned rev acff1444), not git.hush.is;
- the Sapling params are gitignored (not committed, no Git LFS) - the build fetches
  them from the git.dragonx.is/DragonX/zcash-params 'sapling-v1' release and verifies
  their SHA-256 before rust-embed bakes them in (ensure_sapling_params).

For fully offline builds, cargo vendor into lib/vendor/ and add a vendored-sources
redirect (vendor/ is gitignored; the script symlinks it into the prepared dir).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

third_party/silentdragonxlite/silentdragonxlite-cli/lib/Cargo.toml

@@ -0,0 +1,80 @@
+[package]
+name = "silentdragonxlitelib"
+version = "0.1.0"
+edition = "2018"
+
+[features]
+default = ["embed_params"]
+embed_params = []
+
+[dependencies]
+base58 = "0.1.0"
+bs58 = { version = "0.2", features = ["check"] }
+log = "0.4"
+log4rs = "0.8.3"
+dirs = "2.0.2"
+http = "0.2"
+hex = "0.3"
+protobuf = "2"
+byteorder = "1"
+json = "0.12.0"
+tiny-bip39 = "0.6.2"
+secp256k1 = "=0.15.0"
+sha2 = "0.8.0"
+ripemd160 = "0.8.0"
+lazy_static = "1.2.0"
+rust-embed = { version = "5.1.0", features = ["debug-embed"] }
+rand = "0.7.2"
+sodiumoxide = "0.2.5"
+ring = "0.16.9"
+libflate = "0.1"
+subtle = "2"
+threadpool = "1.8.0"
+num_cpus = "1.13.0"
+
+tonic = { version = "0.1.1", features = ["tls", "tls-roots"] }
+bytes = "0.4"
+prost = "0.6"
+prost-types = "0.6"
+tokio = { version = "0.2", features = ["rt-threaded", "time", "stream", "fs", "macros", "uds", "full"] }
+tokio-rustls = { version = "0.12.1", features = ["dangerous_configuration"] }
+webpki = "0.21.0"
+webpki-roots = "0.18.0"
+
+[dependencies.bellman]
+git = "https://git.dragonx.is/DragonX/librustzcash.git"
+rev= "acff1444ec373e9c3e37b47ca95bfd358e45255b"
+default-features = false
+features = ["groth16"]
+
+[dependencies.pairing]
+git = "https://git.dragonx.is/DragonX/librustzcash.git"
+rev= "acff1444ec373e9c3e37b47ca95bfd358e45255b"
+
+[dependencies.zcash_client_backend]
+git = "https://git.dragonx.is/DragonX/librustzcash.git"
+rev= "acff1444ec373e9c3e37b47ca95bfd358e45255b"
+
+default-features = false
+
+[dependencies.zcash_primitives]
+git = "https://git.dragonx.is/DragonX/librustzcash.git"
+rev= "acff1444ec373e9c3e37b47ca95bfd358e45255b"
+default-features = false
+features = ["transparent-inputs"]
+
+[dependencies.zcash_proofs]
+git = "https://git.dragonx.is/DragonX/librustzcash.git"
+rev= "acff1444ec373e9c3e37b47ca95bfd358e45255b"
+default-features = false
+
+[dependencies.ff]
+git = "https://git.dragonx.is/DragonX/librustzcash.git"
+rev= "acff1444ec373e9c3e37b47ca95bfd358e45255b"
+features = ["ff_derive"]
+
+[build-dependencies]
+tonic-build = "0.1.1"
+
+[dev-dependencies]
+tempdir = "0.3.7"