git-filesync 0.21.0

--remote ignores mappings once; dates in commit messages; mv OLD... DIR

Changes:

• --remote (status, pull, diff/difftool, restore, add, set, source
  set-url/set-branch) works against the upstream URL this once, ignoring
  a mapping to a local checkout (source map); the mapping stays. With
  --no-fetch: the cached state.
• Proposed commit messages give every upstream commit id with its date
  (the committer date), the subject's included:
  "[filesync] Sync src/foo.c from owner/lib@a1b2c3d (2026-10-28)",
  "Upstream changes since 3f2a9c1 (2026-09-12):",
  "- Fix off-by-one (9e8d7c6, 2026-10-27)".
• mv OLD... DIR moves several linked files into an existing directory,
  like git mv: all are checked first, then all moved.

Documentation:

• MANUAL: --remote; dates in proposed commit messages; mv OLD... DIR.
• Pinned example versions in README and MANUAL set to v0.21.0.