SOLR-18463: Rename Post Tool and Stream Tool to Post Command and Stream Command

[serhiy-bzhezytskyy]

https://issues.apache.org/jira/browse/SOLR-18463

Description

The ref guide has two pages, post-tool.adoc and stream-tool.adoc, that call bin/solr post and bin/solr stream "the Post Tool" and "the Stream Tool" (and, in two places, the one-word forms PostTool/StreamTool). Both used to be standalone tools, but are now bin/solr subcommands, so the "Tool" framing reads as if they were still separate products.

Solution

Renamed both to "Post Command" and "Stream Command" in the page titles, section headings, and prose across post-tool.adoc, stream-tool.adoc, tutorial-diy.adoc, and streaming-expressions.adoc (13 sites total). All xref:...[] links to these pages use empty link text, so they pick up the new titles automatically.

Left one occurrence untouched: the --help output block on the Post Command page is verbatim output of bin/solr post -h, not authored prose — changing it there would misrepresent what the CLI actually prints. That text lives in PostTool.java and would need a code change, not a doc change.

Tests

Ran ./gradlew :solr:solr-ref-guide:buildLocalAntoraSite and :checkSiteLinks before and after: same 6 pre-existing warnings (unrelated, tracked separately in SOLR-18464/#4922), no new ones, no broken links.

AI-assisted (Claude Sonnet 5).

[serhiy-bzhezytskyy]

@epugh tagging you since this is under SOLR-18459/SOLR-18463, which you filed.