test(debuginfo): add unit tests for debug info store and upload reader

[korniltsev-grafanista-yolo-vibecoder239]

Summary

Adds comprehensive unit tests for the new debug info service (pkg/debuginfo/), which previously had zero test coverage.

• pkg/debuginfo/store_test.go — 9 test functions (~30 subtests) covering the store logic
• pkg/debuginfo/reader/reader_test.go — 4 test functions (~13 subtests) covering the chunked upload reader

What's Tested

Store (store_test.go)

• ValidateGnuBuildID — regex boundary validation (min/max length, valid/invalid hex chars)
• validateInit — init message validation (nil checks, debuginfo type validation, build ID propagation)
• NewStore — constructor validation (bucket required when enabled, optional when disabled)
• ObjectPath / MetadataObjectPath — path construction for object storage
• shouldInitiateUpload — full state machine coverage (first-time, stale upload retry, in-progress, already exists, unknown state error)
• uploadIsStale — staleness threshold boundary cases (startedAt + MaxUploadDuration + 2min)
• fetchMetadata — bucket reads (not-found → nil, valid protojson, corrupt data → error)
• writeMetadata — bucket writes and write-then-fetch round-trip

Upload Reader (reader/reader_test.go)

• Read — single/multiple chunks, empty streams, small buffers, error propagation
• Size — incremental byte tracking
• Context cancellation — before first read and between chunks
• io.ReadAll integration

Approach

• Uses memory.NewInMemBucket() (in-memory object storage) for real bucket behavior rather than mocks
• All tests use t.Parallel() and table-driven patterns per project conventions
• The Upload() streaming handler is not directly tested since it takes a concrete *connect.BidiStream type; instead, all its constituent helper functions are tested individually

🤖 Generated with Claude Code

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Note

Medium Risk
Mostly adds tests, but it also changes the Store.Upload path (error type, proto field names, and explicitly marking metadata STATE_UPLOADED), which could affect client-visible behavior and upload state transitions.

Overview
Adds extensive new test coverage for the debug info subsystem, including unit tests for the chunked UploadReader (chunk boundaries, buffering, size tracking, and context cancellation) and for Store helpers (build-id/init validation, staleness decisions, object paths, and metadata read/write).

Updates Store.Upload to use the renamed proto fields/enums (GnuBuildId, FileMetadata_TYPE_*), return connect.NewError(connect.CodeInternal, ...) instead of gRPC status errors, and to set uploaded metadata to STATE_UPLOADED after a successful bucket upload.

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