docs: merge the hand-written JSON-LD into Mintlify's node

[a-essawy]

Every page carried two Article nodes for one URL. Mintlify generates a full @graph with @id .../slug#article; the hand-written block in each MDX used .../slug/#article — one slash apart, so nothing merged them.

Deleting them was the obvious fix and the wrong one

The hand-written block is the only source of datePublished and author; Mintlify emits neither. Aligning the @id merges the nodes instead — but doing only that would introduce two conflicts on the merged node, so all three changes go together:

change	why
@id: drop the slash before #article	the two nodes merge (30 pages)
remove dateModified	static value vs Mintlify's live build-time one, which now also renders as the visible "Last modified on" stamp. Two values for one property on one node is a conflict.
remove isPartOf	pointed at https://rendobar.com/#website — the apex WebSite node, which does not exist on a docs page. Mintlify already carries the correct isPartOf → /docs#website. (31 pages)

Net: one Article node per page instead of two, now carrying datePublished and author as well.

Two others

• support/faq.mdx is an FAQPage, not an Article. Same trailing-slash @id, and the node was floating unconnected. Now matches the canonical form and points at Mintlify's WebPage node.
• snippets/org-jsonld.mdx deleted. Nothing has ever imported it (grep finds it only in .git/index), and it declared a third Organization plus a fourth WebSite that would have conflicted with both graphs had anything used it.

Test plan

all five validators           PASS
@id base == canonical         32/32, zero mismatches

After merge, confirm one Article node per page in the rendered DOM.