CI: Self-hosted by default while private

[PrzemyslawKlys]

• Run PR checks on self-hosted runners when the repository is private (avoid GitHub-hosted spend limits)
• Keep GitHub-hosted defaults for when the repository becomes public
• Make Claude Code Review optional (skip if token missing; continue-on-error so premium/auth issues don't block)

[intelligencex-review]

IntelligenceX Review

Reviewing PR #165: CI: Self-hosted by default while private
Reviewed commit: 0c8ab8c

Merge blockers: items in Todo List ✅ and Critical Issues ⚠️ sections (if present). Other Issues 🧯 are suggestions.

Workflow-only changes detected (3 workflow files). Head SHA: 0c8ab8c. Review skipped to avoid self-modifying workflow runs. Set allowWorkflowChanges or REVIEW_ALLOW_WORKFLOW_CHANGES=true to override.

Model & Usage 🤖

• Model: gpt-5.3-codex
• Length: medium
• Mode: inline
• Reasoning: not configured
• Usage: unavailable