Add plugin tool recovery diagnostics

[mimeding]

Summary

• Adds read-only diagnostic models and a recovery center service for unavailable plugins, tools, search surfaces, MCP providers, and provider symptoms.
• Preserves trust, provenance, and scope boundaries instead of marking unsafe tools available.
• Adds reporter-safe output with secret, URL, and path redaction.

Validation

• swift test --package-path Packages/OsaurusCore --filter PluginToolCapabilityRecoveryCenterTests
• swiftlint lint --quiet Packages/OsaurusCore/Models/Plugin/PluginToolCapabilityRecovery.swift Packages/OsaurusCore/Services/Plugin/PluginToolCapabilityRecoveryCenter.swift Packages/OsaurusCore/Tests/Plugin/PluginToolCapabilityRecoveryCenterTests.swift
• git diff --check
• External review pass completed; actionable findings were incorporated before publication.
• GitHub checks are green.

Notes

• Ready for review as a read-only diagnostic foundation before visible UI wiring.