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?;

llmx-rs/app-server/tests/suite/user_agent.rs

@@ -26,7 +26,7 @@ async fn get_user_agent_returns_current_llmx_user_agent() -> Result<()> {
 
     let os_info = os_info::get();
     let user_agent = format!(
-        "llmx_cli_rs/0.1.2 ({} {}; {}) {} (llmx-app-server-tests; 0.1.2)",
+        "llmx_cli_rs/0.1.3 ({} {}; {}) {} (llmx-app-server-tests; 0.1.3)",
         os_info.os_type(),
         os_info.version(),
         os_info.architecture().unwrap_or("unknown"),