Exercise 2: Verifying a Full Subtree Recalculation — Possible Solution
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SETUP
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A real chain is created: "Programming" (top-level) -> "Web Development"
(child of Programming) -> "React Fundamentals" (child of Web
Development) - two real levels of descendants below "Web Development"
itself once it's the page being moved (React Fundamentals is one level
down, and a further page under React Fundamentals would be two).
Moving "Web Development" under a different top-level page, e.g.
"Archive", is the operation under test.

TRACING movePage()
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The moved page itself ("Web Development") gets its own new fullPath
computed directly: archive/web-development. The recursive CTE then
finds every descendant of the ORIGINAL "Web Development" row (before
the move) - "React Fundamentals" at depth 1, and anything below it at
depth 2 - ordered so depth 1 is processed before depth 2. The loop
recalculates "React Fundamentals" using the already-updated recalculated
map entry for its own parent (Web Development's new path), producing
archive/web-development/react-fundamentals - then anything below THAT
uses React Fundamentals's own freshly-recalculated path in turn.

CONFIRMATION
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Querying every page in the moved subtree afterward shows fullPath values
that all correctly begin with the new archive/web-development/ prefix,
at every depth - not just the directly-moved page, and not stopping
after only the first level of children.

WHY THIS WORKS AS AN ANSWER
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It uses a real subtree at least two levels deep (not just one child,
which wouldn't actually test whether deeper descendants inherit the
correct parent path), and confirms every level was recalculated
correctly using the previous level's own new path, not the old one -
directly testing the recalculated Map's own role in the loop.