feat: add user-defined command aliases via ~/.bernstein/aliases.yaml

[TheCodingDragon0]

Resubmission of #265 (closed before Pyright fixes landed).

Fixes #249

Extended the alias system to support user-defined aliases loaded from ~/.bernstein/aliases.yaml. User aliases override built-in ones. The �ernstein aliases command now shows whether each alias is built-in or user-defined.

Changes:

• Added _load_user_aliases() to load aliases from YAML
• Added _merge_aliases() called at module load time
• Updated �liases_cmd to show source column (built-in vs user)
• Graceful handling of missing/invalid YAML files
• Pyright strict-mode typing issues resolved

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (1 files)

• src/bernstein/cli/aliases.py - 0 issues

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_{Reviewed by grok-code-fast-1 · 146,863 tokens}

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[chernistry]

This was already merged as part of #264 (including the Pyright fixes). Thanks for resubmitting, but it's all in main already! 👍