fix(cli): survive unavailable chat log directory

[c8dhjp4tyv-bit]

Summary

• prevent logger initialization from crashing the CLI when the current chat directory cannot be created
• keep file logging best-effort while preserving the existing development and production destinations
• add regression coverage for both destinations and the unavailable-chat-directory path

Fixes #783

Validation

• logger.test.ts: 3 passed
• common typecheck: passed
• SDK typecheck: passed
• git diff --check: passed
• full CLI test command: 2,111 passed; existing checkout/environment failures remain in unrelated Infisical, read-only config, and missing release-dependency tests