Major refactoring: UUID-based storage, streaming architecture, and CLI improvements

This commit represents a significant architectural overhaul of vaultik:

Database Schema Changes:
- Switch files table to use UUID primary keys instead of path-based keys
- Add UUID primary keys to blobs table for immediate chunk association
- Update all foreign key relationships to use UUIDs
- Add comprehensive schema documentation in DATAMODEL.md
- Add SQLite busy timeout handling for concurrent operations

Streaming and Performance Improvements:
- Implement true streaming blob packing without intermediate storage
- Add streaming chunk processing to reduce memory usage
- Improve progress reporting with real-time metrics
- Add upload metrics tracking in new uploads table

CLI Refactoring:
- Restructure CLI to use subcommands: snapshot create/list/purge/verify
- Add store info command for S3 configuration display
- Add custom duration parser supporting days/weeks/months/years
- Remove old backup.go in favor of enhanced snapshot.go
- Add --cron flag for silent operation

Configuration Changes:
- Remove unused index_prefix configuration option
- Add support for snapshot pruning retention policies
- Improve configuration validation and error messages

Testing Improvements:
- Add comprehensive repository tests with edge cases
- Add cascade delete debugging tests
- Fix concurrent operation tests to use SQLite busy timeout
- Remove tolerance for SQLITE_BUSY errors in tests

Documentation:
- Add MIT LICENSE file
- Update README with new command structure
- Add comprehensive DATAMODEL.md explaining database schema
- Update DESIGN.md with UUID-based architecture

Other Changes:
- Add test-config.yml for testing
- Update Makefile with better test output formatting
- Fix various race conditions in concurrent operations
- Improve error handling throughout

internal/database/repositories_test.go

@@ -52,7 +52,7 @@ func TestRepositoriesTransaction(t *testing.T) {
 
 		// Map chunks to file
 		fc1 := &FileChunk{
-			Path:      file.Path,
+			FileID:    file.ID,
 			Idx:       0,
 			ChunkHash: chunk1.ChunkHash,
 		}
@@ -61,7 +61,7 @@ func TestRepositoriesTransaction(t *testing.T) {
 		}
 
 		fc2 := &FileChunk{
-			Path:      file.Path,
+			FileID:    file.ID,
 			Idx:       1,
 			ChunkHash: chunk2.ChunkHash,
 		}
@@ -116,7 +116,7 @@ func TestRepositoriesTransaction(t *testing.T) {
 		t.Error("expected file after transaction")
 	}
 
-	chunks, err := repos.FileChunks.GetByPath(ctx, "/test/tx_file.txt")
+	chunks, err := repos.FileChunks.GetByFile(ctx, "/test/tx_file.txt")
 	if err != nil {
 		t.Fatalf("failed to get file chunks: %v", err)
 	}
@@ -218,7 +218,7 @@ func TestRepositoriesReadTransaction(t *testing.T) {
 	var retrievedFile *File
 	err = repos.WithReadTx(ctx, func(ctx context.Context, tx *sql.Tx) error {
 		var err error
-		retrievedFile, err = repos.Files.GetByPath(ctx, "/test/read_file.txt")
+		retrievedFile, err = repos.Files.GetByPathTx(ctx, tx, "/test/read_file.txt")
 		if err != nil {
 			return err
 		}