head: support file-id lookup and full SDK metadata outputs

[goanpeca]

Summary

Let head inspect a specific file version by file-id and expose the full metadata fields the SDK returns for file versions.

Why

head currently works by file name only. That cannot inspect historical versions, hidden versions, or an exact version selected from listFileVersions. The SDK also returns richer metadata than the action currently emits, including encryption, Object Lock, legal hold, and replication status, which are useful for audits and compliance checks.

SDK support (already available)

• B2Object.headById(fileId, options)
• B2Object.getFileInfo(fileId)
• RawClient.getFileInfo(...)
• FileVersion.serverSideEncryption
• FileVersion.fileRetention
• FileVersion.legalHold
• FileVersion.replicationStatus

Proposed surface

New input:

• file-id: when supplied with action: head, inspect that exact version instead of resolving by name.

New/expanded outputs in summary-json and step outputs:

• server-side-encryption
• file-retention
• legal-hold
• replication-status
• exact file-id and file-name

Acceptance criteria

• head can inspect a specific version by file-id.
• Name-based head behavior remains unchanged when file-id is omitted.
• summary-json includes encryption, retention, legal hold, and replication status when the SDK provides them.
• Unauthorized-to-read Object Lock fields are represented clearly without failing unrelated metadata reads.
• Tests cover current-version and historical-version metadata lookup.

Out of scope

• Listing all versions, tracked in list: enumerate all file versions, not just current uploads #93.
• Downloading by file ID, tracked in download: support download by file-id and byte ranges #97.