Add versioned storage methods for incremental export support:
- GetChangesSinceExport: returns changes since a commit hash, with
NeedsFullExport flag for invalid/GC'd commits
- CommitExists: checks if a commit hash exists, supports short prefixes
Also fixes dolt_diff syntax for embedded driver (from_ref, to_ref, table).
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Extends Storage interface with Dolt-specific version control capabilities:
- New VersionedStorage interface in storage/versioned.go with:
- History queries: History(), AsOf(), Diff()
- Branch operations: Branch(), Merge(), CurrentBranch(), ListBranches()
- Commit operations: Commit(), GetCurrentCommit()
- Conflict resolution: GetConflicts(), ResolveConflicts()
- Helper types: HistoryEntry, DiffEntry, Conflict
- DoltStore implements VersionedStorage interface
- New CLI commands:
- bd history <id> - Show issue version history
- bd diff <from> <to> - Show changes between commits/branches
- bd branch [name] - List or create branches
- bd vc merge <branch> - Merge branch to current
- bd vc commit -m <msg> - Create a commit
- bd vc status - Show current branch/commit
- Added --as-of flag to bd show for time-travel queries
- IsVersioned() helper for graceful SQLite backend detection
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
