feat(ostp-client-linux): add CLI VPN client for Linux

New CLI client for Linux with TUN interface support:
- Interactive setup wizard with profile management
- Connect/disconnect commands with root privilege check
- Status monitoring (interface stats, traffic counters)
- Test connection (handshake verification)
- Profile management (add/remove/set-default)
- Anti-VM detection (production mode only)
- Stealth mode (TLS mimicry, geo-SNI selection)

Features:
- Static musl binary (2.0 MB) - universal Linux
- Config storage: ~/.config/ostp/profiles.json
- TUN interface: ostp0 (10.X.Y.Z)
- Security: libc::geteuid() root check, ostp-guard integration
- Error handling: graceful disconnect on Ctrl+C

Commands:
- ostp-client-linux setup             # Interactive wizard
- ostp-client-linux connect --profile default
- ostp-client-linux connect --server 1.2.3.4:443 --psk HEX
- ostp-client-linux status            # Show connection info
- ostp-client-linux disconnect        # Kill running client
- ostp-client-linux profiles list     # List saved profiles
- ostp-client-linux test --server X --psk Y

Distribution updates:
- Added ostp-client-linux (2.0 MB) to linux-x64 package
- Updated SHA256SUMS with all 3 binaries
- Updated README.md with client installation guide
- Rebuilt ostp-server-linux-x64.tar.gz (6.86 MB total)

Note: TUN interface and traffic relay are TODO (placeholders)

Cargo.lock

@@ -429,6 +429,12 @@ version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
 
+[[package]]
+name = "cfg_aliases"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "613afe47fcd5fac7ccf1db93babcb082c5994d996f20b8b159f2ad1658eb5724"
+
 [[package]]
 name = "chacha20"
 version = "0.9.1"
@@ -2428,6 +2434,19 @@ dependencies = [
  "unicode-segmentation",
 ]
 
+[[package]]
+name = "nix"
+version = "0.29.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "71e2746dc3a24dd78b3cfcb7be93368c6de9963d30f43a6a73998a9cf4b17b46"
+dependencies = [
+ "bitflags 2.10.0",
+ "cfg-if",
+ "cfg_aliases",
+ "libc",
+ "memoffset",
+]
+
 [[package]]
 name = "nodrop"
 version = "0.1.14"
@@ -2916,6 +2935,27 @@ dependencies = [
  "tracing-subscriber",
 ]
 
+[[package]]
+name = "ostp-client-linux"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "clap",
+ "console",
+ "dialoguer",
+ "hex",
+ "libc",
+ "nix",
+ "osn",
+ "ostp",
+ "ostp-guard",
+ "serde",
+ "serde_json",
+ "tokio",
+ "tracing",
+ "tracing-subscriber",
+]
+
 [[package]]
 name = "ostp-daemon"
 version = "0.1.0"