fix(plugin): restore disabled etag installs as active replacement

[FinleyGe]

Summary

• allow direct URL install to reactivate a disabled plugin with the target ETag
• enforce only one active ETag per pluginId/version by disabling replaced active plugins
• keep plugin_installations aligned by deleting old ETag installations and upserting the restored system installation
• keep usecase replacement cleanup focused on runtime unregister after repo-level DB replacement

Tests

• ./node_modules/.bin/vitest run packages/infrastructure/src/plugin/plugin.repo.test.ts packages/usecase/src/usecase.test.ts
• ./node_modules/.bin/tsc --noEmit
• git diff --check

[github-actions]

Build Successful - Preview Server image for this PR:

ghcr.io/labring/fastgpt-plugin-pr:server_7a4cecb06cc2b44a18cab0eb7334967bf19e8182

Time: 2026-07-07 17:08:41 (UTC+8)