Fix importfeeds to continue on symlink creation failures

[sammydynamo-dev]

Description

Fixes #840.

When importfeeds is configured with formats: link, it creates a symlink for each imported track. If that symlink can't be created — on Windows without the privilege to make symlinks (the original report), but also on any OS when the destination directory isn't writable or the filesystem doesn't support symlinks — beets.util.link() raises FilesystemError. That exception wasn't caught, so it propagated out of the import pipeline and aborted the entire beet import run, even though the tracks had already been imported into the library.

This wraps the link() call in ImportFeedsPlugin._record_items() in try/except FilesystemError, logs a per-item warning, and continues with the remaining items — so a failed symlink is skipped rather than fatal. This is the "catch and skip" behaviour suggested in the issue thread. It catches FilesystemError (not OSError, which util.link() wraps) and mirrors the existing handling in beetsplug/playlist.py and the fetchart fix (#6193).

Adds five regression tests (warn-and-continue, that remaining items are still linked, that only FilesystemError is caught, and that a successful link still creates the symlink). Also verified manually: with a read-only feeds directory, beet import now finishes with a warning (exit 0) instead of aborting (exit 1), and the track is still imported.

To Do

• Documentation (bugfix; no user-facing flag or config changed)
• Changelog
• Tests

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.81%. Comparing base (c90f42d) to head (75e6724).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6765      +/-   ##
==========================================
+ Coverage   74.78%   74.81%   +0.03%     
==========================================
  Files         163      163              
  Lines       20966    20969       +3     
  Branches     3302     3302              
==========================================
+ Hits        15680    15689       +9     
+ Misses       4529     4523       -6     
  Partials      757      757              

Files with missing lines	Coverage Δ
beetsplug/importfeeds.py	86.25% <100.00%> (+5.73%)	⬆️

... and 1 file with indirect coverage changes

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[sammydynamo-dev]

Hi @snejus 👋 — this is my first contribution to beets.

This PR (#6765) fixes #840: when importfeeds is set to formats: link and a
symlink can't be created (e.g., on Windows, or into a read-only directory), the Failure is now logged as a per-item warning, and the import continues, instead of
The unhandled FilesystemError aborted the whole beet import run. It follows
the same warn-and-skip pattern as the fetchart fix (#6662) and playlist.py.

It includes five regression tests and a changelog entry, and the full test suite
passes locally. I tagged you since you reviewed the very similar fetchart change —
No rush at all, but I'd appreciate a review whenever you have time. Thanks!