Fix method should update all redirects in chain, not just the source

Problem/Motivation

When fixing redirect chains (A → B → C → D), the fixChain() method only updates the source redirect (A), leaving intermediate redirects (B and C) unchanged. This causes residual sub-chains to be detected on subsequent audits.

Example scenario:

• Initial state: A → B → C → D (chain detected)
• After fix: A → D (only source updated)
• Problem: B → C → D sub-chain still exists
• Next audit detects: B → C → D as a new chain

This creates an inefficient workflow where multiple fix operations are needed to resolve all chains, and can confuse site administrators who expect all chain issues to be resolved in a single fix operation.