v0.0.7: Chunked encrypted file transfer

Protocol:
- WireMessage::FileHeader { id, sender_fp, filename, file_size, total_chunks, sha256 }
- WireMessage::FileChunk { id, sender_fp, filename, chunk_index, total_chunks, data }
- 64KB chunks, SHA-256 integrity verification

CLI TUI:
- /file <path> command: reads file, chunks, encrypts each with ratchet, sends
- Progress display: "Sending file.pdf [3/10]..."
- Incoming file reassembly with chunk tracking
- SHA-256 verification on complete
- Saves to data_dir/downloads/
- Max file size: 10MB

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

warzone/Cargo.lock

@@ -2647,7 +2647,7 @@ dependencies = [
 
 [[package]]
 name = "warzone-client"
-version = "0.0.6"
+version = "0.0.7"
 dependencies = [
  "anyhow",
  "argon2",
@@ -2665,6 +2665,7 @@ dependencies = [
  "reqwest",
  "serde",
  "serde_json",
+ "sha2",
  "sled",
  "tokio",
  "tokio-tungstenite",
@@ -2679,7 +2680,7 @@ dependencies = [
 
 [[package]]
 name = "warzone-mule"
-version = "0.0.6"
+version = "0.0.7"
 dependencies = [
  "anyhow",
  "clap",
@@ -2688,7 +2689,7 @@ dependencies = [
 
 [[package]]
 name = "warzone-protocol"
-version = "0.0.6"
+version = "0.0.7"
 dependencies = [
  "base64",
  "bincode",
@@ -2711,7 +2712,7 @@ dependencies = [
 
 [[package]]
 name = "warzone-server"
-version = "0.0.6"
+version = "0.0.7"
 dependencies = [
  "anyhow",
  "axum",
@@ -2738,7 +2739,7 @@ dependencies = [
 
 [[package]]
 name = "warzone-wasm"
-version = "0.0.6"
+version = "0.0.7"
 dependencies = [
  "base64",
  "bincode",