Improve error messages

[dogancanbakir]

Description

Improve error messages throughout the codebase to be more user-friendly and actionable.

Areas to improve

• Provider not found errors - suggest available providers
• Language detection failures - show detected alternatives
• Timeout errors - include timeout value and suggest increasing
• Connection errors - include troubleshooting steps
• Missing dependencies - show installation instructions

Example

Instead of:
```
Error: provider not found
```

Show:
```
Error: provider "foo" not found

Available providers:

• docker (default)
• wasmer
• podman
• nsjail (Linux only)
• gvisor (Linux only)
• firecracker (Linux only)
  ```

Files to review

• errors.go
• internal/factory/factory.go
• Provider implementations