Track pCloud stability dependency on OpenDAL PR #7617

[mro68]

Summary

Track pCloud stability in rustic_core as blocked by an OpenDAL fix that is not yet released.

Related upstream dependency PR:
apache/opendal#7617

Related rustic issue:
rustic-rs/rustic#1774

Problem statement

pCloud backend support is enabled, but practical reliability depends on OpenDAL changes from PR #7617.
Until that PR is merged and part of a released OpenDAL version consumed by rustic_core, pCloud behavior can remain unreliable in real-world workflows.

Proposed tracking tasks

1. Keep this issue open as dependency blocker for stable pCloud support.
2. After OpenDAL release containing #7617, bump OpenDAL dependency in rustic_core.
3. Verify pCloud operations in regression coverage.
4. If needed, document pCloud as experimental until the dependency lands.

Acceptance criteria

• OpenDAL release with #7617 is available.
• rustic_core dependency bump is merged.
• pCloud regression validation passes.

Environment

• OS: Linux
• Project: rustic-rs/rustic_core

[mro68]

Clarification: this is not Linux-only.

I have now also tested on Windows, and the same pCloud reliability problems are reproducible there as well.
So this should be treated as a cross-platform issue (at least Linux + Windows), likely tied to shared backend behavior rather than OS-specific behavior.