Summary

• add the index115 consumer service with browse, search, link, and read-only WebDAV endpoints
• wire index115 runtime/config/bootstrap into PowerList and add sqlite plus bleve backed search handling
• harden the consumer runtime by degrading when bleve is unavailable, tightening error mapping, fixing manifest path resolution, and cleaning up transferred 115 files by received file id

Test Plan

• go test ./internal/index115 -v
• go test ./internal/bootstrap -run 'TestInitIndex115Service(ReturnsErrorWhenManifestMissing|UsesConfiguredPaths|DegradesWhenBleveUnavailable)' -v
• go test ./server/handles -run 'TestIndex115(SearchRejectsEmptyQuery|BrowseRootReturnsSuccess|LinkBindsRequestBody|SearchReturns503WhenSearcherUnavailable|LinkReturns404ForMissingFile|LinkReturns401ForInvalidCookie)' -v
• go test ./server -run 'TestIndex115WebDAV' -v

Notes

• full go test ./... is currently blocked by pre-existing repository issues and environment dependencies outside this change, including non-constant format string build failures in unrelated packages, missing fuse.h for internal/fuse, and pkg/aria2/rpc tests requiring a local service on port 6800