fix(node): scope _enriched_attempted by group, not just content hash0.7

Major finding: entry.id is a content hash, so the exact same physical
file — the same MP3, byte-for-byte — indexed into two different groups
(a shared library reused across several demo/test groups, or genuinely
the same folder shared into two groups) produces the *same id* in both.
_enriched_attempted was a single flat set of bare ids shared across every
group this node hosts. The moment one group's copy got enriched, every
other group's otherwise-identical copy read as "already attempted" and
was skipped forever — nothing else ever revisits an id once it's in this
set. That group's Music tab (or Videos tab, same bug, same set) showed
every affected file at duration 0 with no artist/album/thumbnail,
permanently, no matter how long you waited or how many times you
reloaded — group A having been enriched first was enough to silently
starve every later group of the same content.

Now keyed by (group_id, entry.id) throughout — the enrichment gate, the
sweep, and the rename re-enrichment path, for both video and audio (they
already shared the one set, and the collision risk is identical for
both). New regression test constructs two groups with byte-identical
audio content and confirms both enrich independently.

0 files changed, 0 insertions, 0 deletions