enhance: Client-side direct read for sealed segments from Object Storage

[tinswzy]

Background
In Woodpecker, sealed segments are immutable and have already been fully uploaded to object storage (e.g. S3).
Currently, even for catch-up reads that only target sealed segments, clients still need to go through quorum nodes to read data.

This introduces unnecessary:

• network hops
• quorum node load
• tail latency
  For sealed segments, quorum involvement is no longer required for correctness.

Proposal
Introduce a new read path: Clients can directly read sealed segment data from Object Storage, bypassing quorum nodes entirely.

Specifically:

• For reads that only involve sealed segments
• Client fetches segment metadata (location, offsets, checksums)
• Client directly issues GET / range GET requests to Object Storage (S3)
• Quorum nodes are skipped for data plane