fix(storage): stream job output in real-time with StdoutPipe/StderrPipe

- Replace blocking outBuf/errBuf capture with StdoutPipe+StderrPipe + goroutines
- scanAndEmit runs in parallel for stdout and stderr, emitting each line
  via SSE broadcast and DB append immediately (not after cmd.Run completes)
- Custom scanner split: bytes.TrimRight strips trailing \r so snapraid
  progress lines (e.g. '2%, 57396 MB\r') are stored as clean lines
- scanner.Buffer increased to 128KB max to handle large outputs
- Use sync.WaitGroup to ensure both scanners finish before MarkJobFinished
- Fix PID capture: cmd.Process is nil before cmd.Start(), pass 0 instead

Makefile

@@ -1,5 +1,5 @@
 BINARY=nasctl
-VERSION?=0.8.1
+VERSION?=0.8.2
 GO?=go
 LDFLAGS=-s -w -X github.com/darroyo/nasctl/internal/web.Version=$(VERSION) -X github.com/darroyo/nasctl/internal/web.Commit=$(shell git rev-parse --short HEAD 2>/dev/null || echo unknown)
 BUILD_FLAGS=CGO_ENABLED=0