chore: Bump version to 0.1.3

- Fix: Skip empty/whitespace-only text content blocks in chat completions
- This resolves Anthropic API errors:
  - "messages: text content blocks must contain non-whitespace text"
  - "messages: text content blocks must be non-empty"
- Updated version strings in all test files and snapshots

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

llmx-rs/app-server/tests/common/mcp_process.rs

@@ -138,7 +138,7 @@ impl McpProcess {
             client_info: ClientInfo {
                 name: "llmx-app-server-tests".to_string(),
                 title: None,
-                version: "0.1.2".to_string(),
+                version: "0.1.3".to_string(),
             },
         })?);
         let req_id = self.send_request("initialize", params).await?;