sync: Return SyncResult from update_repo()

[tony]

Summary

update_repo() across all three VCS sync classes (Git, Hg, SVN) now returns a SyncResult instead of None. This lets callers distinguish successful syncs from failures and inspect structured error details — instead of errors being silently swallowed or bubbling as uncaught exceptions.

What changed

• New dataclasses in sync/base.py: SyncResult (tracks ok status + error list) and SyncError (records step name, message, and original exception)
• GitSync.update_repo(): All 10+ except CommandError: return paths now record errors in SyncResult with labeled steps (fetch, rebase, checkout, stash-save, etc.) and preserve the original early-return vs. continue-on-error control flow
• HgSync.update_repo() and SvnSync.update_repo(): Updated for API consistency — wrap obtain and pull/update failures in SyncResult
• GitRemoteRefNotFound: Added __str__() override to avoid AttributeError when the parent CommandError.__str__() expects cmd/returncode attributes that this subclass doesn't set

Additional fixes included

• Git.rev_list(): Fixed _all parameter reference that was shadowed by the builtin all
• rev-list disambiguation: Use fully-qualified refs/heads/ paths when a local branch name collides with a filesystem path
• Invalid-upstream rebase: Return early with error instead of falling through to stash-pop on an already-failed rebase
• Ruff config: Moved A002 suppression from inline comment to per-file-ignores in pyproject.toml
• Test isolation: test_update_repo_pull_failure_returns_sync_result (hg) now uses the create_hg_remote_repo factory instead of deleting the session-scoped hg_remote_repo fixture

Design decisions

• Errors as values, not exceptions: SyncResult follows the structured result pattern. Git's update_repo() already caught and discarded CommandError at every step — this makes those outcomes inspectable rather than silent
• Preserved control flow: Each error handler keeps the original behavior. fetch failure returns early (fatal). stash-save failure continues (non-fatal). rev-list HEAD failure on initial repos returns ok=True (benign — nothing to do)
• Best-effort recovery: Uses contextlib.suppress(CommandError) for cleanup operations that may fail (rebase abort, stash pop, reset) — matching git's own philosophy of trying cleanup but not failing if it doesn't work

Test plan

• test_update_repo_success_returns_sync_result — ok=True on successful sync
• test_update_repo_fetch_failure_returns_sync_result — fetch failure captured in SyncResult
• test_update_repo_symbolic_ref_failure_returns_sync_result — symbolic-ref failure path
• test_update_repo_checkout_failure_returns_sync_result — checkout error detection
• test_update_repo_stash_save_failure_returns_sync_result — stash-save failure continues
• test_update_repo_rev_list_head_failure_returns_sync_result — rev-list HEAD failure path
• test_update_repo_pull_failure_returns_sync_result (hg) — pull failure with disposable remote
• test_update_repo_update_failure_returns_sync_result (svn) — update failure path
• test_rev_list_all_parameter — verifies _all parameter fix
• All 577 tests pass, mypy clean, ruff clean

Companion PR

• vcspull: cli/sync: Detect and report errored git syncs via SyncResult vcspull#512 (checks SyncResult and reports failures to users)

[codecov]

Codecov Report

❌ Patch coverage is 89.21569% with 55 lines in your changes missing coverage. Please review.
✅ Project coverage is 57.07%. Comparing base (3d850eb) to head (bca6778).
⚠️ Report is 22 commits behind head on master.

Files with missing lines	Patch %	Lines
src/libvcs/sync/svn.py	0.00%	15 Missing ⚠️
tests/sync/test_svn.py	0.00%	14 Missing ⚠️
src/libvcs/sync/base.py	18.75%	13 Missing ⚠️
src/libvcs/sync/git.py	88.37%	9 Missing and 1 partial ⚠️
src/libvcs/sync/hg.py	82.35%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #514      +/-   ##
==========================================
+ Coverage   53.48%   57.07%   +3.58%     
==========================================
  Files          38       38              
  Lines        5704     6166     +462     
  Branches     1062     1069       +7     
==========================================
+ Hits         3051     3519     +468     
+ Misses       2143     2126      -17     
- Partials      510      521      +11     

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[tony]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

🤖 Generated with Claude Code

[tony]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

🤖 Generated with Claude Code

_{- If this code review was useful, please react with 👍. Otherwise, react with 👎.}

[tony]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

Reviewed: error handling in sync/git.py, sync/hg.py, sync/svn.py; SyncResult/SyncError dataclasses in sync/base.py; rev_list parameter fix in cmd/git.py; GitRemoteRefNotFound exception refactor; test coverage across 13 error steps; public exports in init.py.

🤖 Generated with Claude Code

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