- Decode each row independently so one corrupt entry no longer aborts
the whole address-book iterator
- Log a warn with the raw `value` and continue past parse failures
- Add a regression test that mimics the post-migration-8 state where a
legacy `[]:8776` row lands as `type='ipv6'`
A pre-`df8e4e6c` parser admitted `[]:8776` as `HostName::Dns("[]")`.
Migration 8 retyped any `[..]:N` dns row to `ipv6` without validating
the inner part, so on read `Address::from_str` rejects the row with
"invalid IPv6 address syntax", which bubbled up and caused
`available_peers()` to silently return empty, breaking peer discovery
for the affected node.
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