chore(daemon): track upstream voxora-hf .complete marker content-addressing

# chore(daemon): track upstream voxora-hf .complete marker content-addressing

## Problem
`voxora-hf::resolve_single_file` uses a `.complete` marker file
inside the cache directory to record that a model download finished
without committing the file's identity to the marker. The current
upstream design ties the marker's presence to the directory, not to
the file it claims to describe — so a partial download that writes
the marker before the actual blob (or a stale marker left behind by
a crashed download) can satisfy the "is this model cached?" check
without the file being present or correct.

The telora daemon side has a `refuse_if_symlink` mitigation
(v0.2.0's structural fix for airvzxf/telora#79) that rejects a
cache whose `.complete` marker is set but the requested file is
missing. That fix papers over the upstream design weakness; the
underlying weakness — that the marker is not content-addressed —
remains. A future voxora release could make the marker filename
itself a content hash (so a `.complete` named after file X can only
exist if file X exists with that hash), which would let downstream
consumers drop the missing-file guard.

This issue is **tracking-only**: it does not require a telora PR.
It exists so the design weakness is visible in our issue tracker
when a voxora release is reviewed, and so we don't accidentally
regress the `refuse_if_symlink` mitigation while assuming upstream
fixed it.

## Where
- Upstream: voxora-hf `resolve_single_file` (no commit SHA tracked
here; tracked in the linked voxora issue).
- telora-daemon's `refuse_if_symlink` mitigation lives near the
`voxora-hf` cache lookups; keep it intact until upstream closes
the marker issue.

## Why now
Surfaced during F2 review (item #9). Deferred to keep v0.1.3
shippable. Tracking-only; no immediate work, but the operator
benefits from having the design weakness on the record.

## Acceptance criteria
- A comment in `telora-daemon/Cargo.toml` (or the daemon source
where `voxora-hf` is used) notes that the
`refuse_if_symlink`-style mitigation is a workaround for the
upstream `.complete` marker design weakness.
- This issue is linked from any future voxora-bump PR (A6) so the
reviewer is prompted to re-evaluate.
- When the upstream voxora issue is filed and closed, this issue is
closed with a comment referencing the upstream fix.

## Related
- Part of #86
- v0.1.3 release:
- Related: airvzxf/telora#79 (the latent bug the daemon-side mitigation closes)
- Related: A6 (next voxora bump is the natural moment to revisit this)