feat: promote eight core character stats

[JOY (JOY)]

Summary

• Promote the MVP core stat contract to eight stats: strength, dexterity, endurance, perception, focus, presence, intelligence, and luck.
• Keep agility, force, vitality, and resilience as compatibility aliases while runtime consumers migrate.
• Carry intelligence, luck, and canonical dexterity through Nakama normalization, tests, Unity DTOs, NetworkPlayer state, prototype NPC speed logic, and HUD display.
• Update GDD, character profile docs, roadmap, changelog, and vertical slice docs so wisdom remains out and perception covers the wisdom-like role.

Local review

• Local codex review --uncommitted: clean, no actionable findings.
• Unity console check through MCP: no C# compile errors found; existing logs are imported asset serialization/material warnings and RelayService warning.

Verification

• cmd /c npm run build in backend/nakama
• cmd /c npm test in backend/nakama
• npx --yes markdownlint-cli2 README.md ROADMAP.md CHANGELOG.md CONTRIBUTING.md SECURITY.md AGENTS.md .claude/CLAUDE.md "docs/**/*.md"
• git diff --check
• Unity MCP console check for C# errors