feat(fs): add pipelined multipart upload (#2723)

* feat(multipart): add chunk reassembly window

- Reassemble concurrently uploaded chunks into a sequential stream through a ring file, bounding disk usage to slots*chunkSize per session
- Park writers up to a deadline when their slot is busy instead of rejecting instantly, so flow control does not surface as connection errors in browsers
- Record a per-chunk CRC32 table for re-fill verification and keep it readable after close
- Propagate cancellation to blocked readers via CloseWithError so drivers treat aborts like canceled requests
- Cover ordering, backpressure, idempotent resends and close/abort wake-ups with race-enabled tests

* feat(multipart): add pipelined upload session manager

- Start the driver upload at session init over a sequential stream backed by the window, so client-to-server and server-to-storage transfers run concurrently
- Attach client-provided hashes to the stream so drivers can attempt rapid upload before any chunk arrives, and absorb chunks racing pipeline completion idempotently
- Keep only metadata and chunk CRCs after a failed attempt: re-sending chunk 0 re-fills a fresh window, and content changes between attempts are rejected
- Resume receiving sessions only when client hashes prove the same file; failed_retriable sessions resume unconditionally
- Reclaim sessions with a sliding-TTL GC and sweep orphaned ring files at startup
- Cover the state machine with race-enabled tests over a stubbed storage layer

* feat(setting): add multipart upload settings

- Add multipart_enabled and multipart_chunk_size (MB) as public traffic settings
- Validate the chunk size on save (integer within 1-90) via the setting item hook

* feat(server): add multipart upload API

- Add /api/fs/multipart init/chunk/complete/status/abort endpoints with headers aligned with /fs/put
- Gate init behind the FsUp permission checks and reuse the client upload rate limiter for chunk uploads
- Drain the request body before answering chunk requests on every path, so browsers do not see early responses as network errors
- Start the multipart session GC when the router is initialized to reclaim ring files orphaned by a previous run

* refactor(multipart): remove unused overwrite session field

- The overwrite flag was stored on the session but never read: the handler
  performs the pre-check and op.Put owns the overwrite semantics

* feat(setting): allow any positive multipart chunk size

- Validate the setting as a positive integer only; self-hosted admins decide
  the ceiling themselves instead of an arbitrary 90MB cap
- Keep clamping the client-suggested X-Chunk-Size to the admin value: the
  server buffers a window of 8 chunks per session, so an unbounded client
  suggestion would translate directly into server-side disk usage

* refactor(server): simplify multipart chunk size clamp

- Fold the two-step clamp into one branch: the ceiling is already floored,
  so a client suggestion just lowers the size with a 1MB floor

Author: thetapilla

internal/bootstrap/data/setting.go

@@ -249,6 +249,8 @@ func InitialSettings() []model.SettingItem {
 		{Key: conf.StreamMaxClientUploadSpeed, Value: "-1", Type: conf.TypeNumber, Group: model.TRAFFIC, Flag: model.PRIVATE},
 		{Key: conf.StreamMaxServerDownloadSpeed, Value: "-1", Type: conf.TypeNumber, Group: model.TRAFFIC, Flag: model.PRIVATE},
 		{Key: conf.StreamMaxServerUploadSpeed, Value: "-1", Type: conf.TypeNumber, Group: model.TRAFFIC, Flag: model.PRIVATE},
+		{Key: conf.MultipartEnabled, Value: "true", Type: conf.TypeBool, Group: model.TRAFFIC, Flag: model.PUBLIC},
+		{Key: conf.MultipartChunkSize, Value: "10", Type: conf.TypeNumber, Group: model.TRAFFIC, Flag: model.PUBLIC, Help: `chunk size of multipart upload in MB (positive integer), keep it under your CDN's request body limit; each active session buffers up to 8 chunks on the server's disk`},
 	}
 	additionalSettingItems := tool.Tools.Items()
 	// 固定顺序

internal/conf/const.go

@@ -164,6 +164,8 @@ const (
 	StreamMaxClientUploadSpeed            = "max_client_upload_speed"
 	StreamMaxServerDownloadSpeed          = "max_server_download_speed"
 	StreamMaxServerUploadSpeed            = "max_server_upload_speed"
+	MultipartEnabled                      = "multipart_enabled"
+	MultipartChunkSize                    = "multipart_chunk_size"
 )
 
 const (