fix(cli): make mcp url truncation utf8 safe

[OnlyYu1996]

Summary

• replace raw byte-index truncation in MCP list/auth display with a UTF-8 safe helper
• preserve the existing ASCII display widths for MCP HTTP URLs, auth-list URLs, and stdio commands
• cover short strings, legacy ASCII truncation lengths, UTF-8 boundary safety, and tiny-width handling

Bounty issues:

• [BUG] [v0.0.1] mcp list URL display truncation uses unsafe byte slice url[..22] — panics on multi-byte UTF-8 URLs PlatformNetwork/bounty-challenge#52380
• [BUG] [v0.0.1] mcp auth list URL column uses unsafe byte slice url[..35] — panics on multi-byte UTF-8 URLs PlatformNetwork/bounty-challenge#52408

Validation

• cargo +stable fmt --package cortex-cli --check
• cargo +stable test --package cortex-cli mcp_cmd::tests:: -- --nocapture (4 passed)
• cargo +stable test --package cortex-cli mcp_cmd:: -- --nocapture (194 passed)
• cargo +stable check --package cortex-cli --lib
• cargo +stable build --package cortex-cli --bin Cortex
• git diff --check

Note: an end-to-end debug-binary smoke for mcp list / mcp auth list is blocked on current main by the existing clap debug assertion Command mcp: command ls alias ls is duplicated before command dispatch. The UTF-8 truncation behavior is covered in unit tests and the binary still builds successfully.

[greptile-apps]

Your free trial has ended. If you'd like to continue receiving code reviews, you can add a payment method here.