Emit server.kb_version in component scan (-C) output

[mscasso-scanoss]

Problem

scanoss -C (component_scan in src/purl_scan.c) serves /scan/components, the call batchScanner uses to fetch component details for a scan. Its output has no KB version:

{"results": [{"url_hash": "...", "component": {...}}, ...]}

Because of that, batchScanner cannot fill server.knowledge_base in its report (scanoss/batchScanner#7). Clients such as Earnie need the KB version to reuse cached OSS matches between scans. Today they work around it with a dummy POST /scan/direct, because only that path emits server.kb_version.

-P (/scan/raw) and the snippet scan don't emit it either.

Proposal

Add a server block to the -C output, after results:

{
  "results": [ ... ],
  "server": {
    "version": "6.0.0-crc64",
    "kb_version": {"monthly": "26.09", "daily": "26.09.27"}
  }
}

• The data is already there: initialize_ldb_tables() calls kb_version_get() before -C runs, so the global kb_version is loaded. version is SCANOSS_VERSION.
• Emit only version and kb_version. Do not add hostname, flags or elapsed as print_server_stats() does. batchScanner calls -C in several batches, and every batch should return the same block.
• Keep the current fallback. When /var/lib/ldb/<db>/version.json is missing, kb_version is the string "N/A". Consumers must accept both the object and that string.
• Respect quiet in the same way results does.

The change is additive. Existing consumers read only results.

Acceptance

• scanoss -C <hash>[,<hash>...] returns valid JSON with results and server.{version,kb_version}.
• kb_version matches the contents of version.json for the loaded DB, or is "N/A" when that file is missing.
• The output is unchanged for invalid or empty input (exit code and message).

Follow-up

• batchScanner maps this block to its report schema: api_version, knowledge_base.monthly_version and knowledge_base.daily_version (scanoss/batchScanner#7).
• Check that the HTTP layer serving /scan/components passes the server key through unchanged.