feat(opaq): update plugin for sensitivity levels and scoped entries

[moukrea]

Summary

• Bump opaq plugin version to 0.3.0
• CLAUDE.md: update Rule 1 (mention opaq reveal), add Rule 6 (opaq reveal for plain entries), add Rule 7 (respect scope resolution)
• bash-guard.sh: block shadows and cleanup commands, keep reveal allowed, update denial message
• SKILL.md: add Step 2b workflow for opaq reveal, add reveal examples, update agent-accessible commands list

Companion PR to moukrea/opaq#2 which adds sensitivity levels and location-aware scoped entries to the opaq binary.

Test plan

• Verify bash-guard blocks opaq shadows and opaq cleanup
• Verify bash-guard allows opaq reveal
• Verify SKILL.md workflow covers both run and reveal paths