[UX] Improved error messages with actionable suggestions

[jwesleye]

Feature Description

Better error messages that suggest fixes and link to docs.

Problem/Motivation

Current errors can be cryptic. Users don't know how to fix issues.

Proposed Solution

Instead of:

Error: ANTHROPIC_API_KEY not found

Show:

Error: ANTHROPIC_API_KEY not found

To fix:
  1. Get API key from: https://console.anthropic.com/
  2. Run: export ANTHROPIC_API_KEY=your-key-here
  3. Or add to .env file

Docs: https://docs.claude.com/...

Benefits

• Self-service troubleshooting
• Better onboarding
• Less support burden
• Professional experience

Priority

• Critical
• High
• Medium
• Low

[github-actions]

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Thank you for your contributions!