docs: fix links to archived pre-reorg pages

Docs: Clean up

Drop the Building Applications and Advanced Topics sidebar groups and
the Core leftover pages that sit outside the target Concepts list.
Copies stay in _ARCHIVE. Retarget the two live links that pointed at
archived pages to the API reference.

Docs: Add Accounts concepts page and examples

# Conflicts:
#	docs/sidebar.config.json
#	docs/src/content/docs/concepts/core/account.md

Docs: Add Errors and Debugging concepts page and examples

# Conflicts:
#	docs/sidebar.config.json

Docs: Add Transaction concepts page and examples

gitpython 3.1.50 has 15 known CVEs. Add an explicit minimum version constraint
following the established pattern for pygments, requests, and filelock.

Co-authored-by: JBScaled <164410456+JBScaled@users.noreply.github.com>

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