#64 feat(#62): DRY OAuth support for all providers in provision_auth

[Anonymous]

Originally created by: kumaakh

Summary

• Extends ProviderAdapter with oauthCredentialFiles(), oauthSettingsMerge(), and oauthEnvVarsToUnset() — provider-generic OAuth interface
• Gemini: copies 3 OAuth files, deep-merges settings.json (no overwrite), unsets GEMINI_API_KEY from remote shell profiles
• Claude: migrated to new interface (behavior unchanged)
• Codex/Copilot: stubs returning null/[]
• provision_auth: branching is now api_key → provisionApiKey, oauthCredentialFiles() → provisionOAuthCopy, else collectOobApiKey — zero hardcoded provider paths
• remove_member: loops provider.oauthCredentialFiles() for cleanup
• deepMergeJson / readRemoteJson helpers in os-commands.ts
• member_detail / list_members: auth mode shows oauth, api-key, or warning when both present

Test plan

• [ ] CI passes (build + 613 tests)
• [ ] provision_auth on Gemini member (no api_key) copies all 3 OAuth files and merges settings.json
• [ ] provision_auth on Claude member unchanged
• [ ] remove_member cleans up OAuth files for any provider
• [ ] member_detail shows correct auth mode

Closes [#62]

🤖 Generated with Claude Code

[Anonymous]

Originally posted by: kumaakh

Merged into integration/schema-oauth

[Anonymous]

Ticket changed by: kumaakh

• status: open --> closed