fix(skill-context): gate discovered browser skills by provider

[code-yeongyu]

Summary

• prevent discovered provider-gated browser skills from overriding the selected builtin browser provider in createSkillContext
• add a regression test proving agent-browser no longer reintroduces a discovered playwright skill

Verification

• bun test src/plugin/skill-context.test.ts src/features/opencode-skill-loader/skill-content.test.ts src/features/builtin-skills/skills.test.ts
• bun run typecheck
• bun run build
• manual QA: loaded createSkillContext with browser_automation_engine.provider = "agent-browser" and a discovered .claude/skills/playwright; confirmed hasPlaywright: false and hasAgentBrowser: true

---

Summary by cubic

Fixes a bug where discovered browser skills could override the configured provider in createSkillContext. Only the skill matching browser_automation_engine.provider is included, preventing playwright from superseding agent-browser.

• Bug Fixes
  • Gate provider-specific browser skills to the selected provider (agent-browser, playwright).
  • Filter discovered skills across all sources before merging to honor the configured provider.
  • Add a regression test verifying browser_automation_engine.provider = "agent-browser" ignores a discovered playwright skill.

^{Written for commit 1528e46. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 2 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

_{Auto-approved: The fix correctly gates discovered browser skills to the configured provider using a safe filter and includes a regression test. No impact on non-browser skills.}