Consolidate docs: rewrite README as primary reference, remove TODO.md

README now covers: storage backends (s3/file/rclone), all CLI commands
with full flag docs, configuration reference table, architecture overview,
roadmap (post-1.0 only), and development workflow.

TODO.md removed — completed items dropped, remaining roadmap items
merged into README.

ARCHITECTURE.md updated: correct snapshot ID format, storage.Storer
instead of s3.Client, binary SQLite export instead of SQL dump.

ARCHITECTURE.md

@@ -53,8 +53,8 @@ The database tracks five primary entities and their relationships:
 ### Entity Descriptions
 
 #### File (`database.File`)
-Represents a file or directory in the backup system. Stores metadata needed for restoration:
-- Path, mtime
+Represents a file, directory, or symlink in the backup system. Stores metadata needed for restoration:
+- Path, source_path (for restore path stripping), mtime
 - Size, mode, ownership (uid, gid)
 - Symlink target (if applicable)
 
@@ -95,7 +95,7 @@ Maps chunks to their position within blobs:
 
 #### Snapshot (`database.Snapshot`)
 Represents a point-in-time backup:
-- `ID`: Format is `{hostname}-{YYYYMMDD}-{HHMMSS}Z`
+- `ID`: Format is `{hostname}_{snapshot-name}_{RFC3339}` (e.g. `server1_home_2025-06-01T12:00:00Z`)
 - Tracks file count, chunk count, blob count, sizes, compression ratio
 - `CompletedAt`: Null until snapshot finishes successfully
 
@@ -127,7 +127,7 @@ fx.New(
     config.Module,                                   // 5. Config
     database.Module,                                 // 6. Database + Repositories
     log.Module,                                      // 7. Logger initialization
-    s3.Module,                                       // 8. S3 client
+    storage.Module,                                  // 8. Storage backend (S3/file/rclone)
     snapshot.Module,                                 // 9. SnapshotManager + ScannerFactory
     fx.Provide(vaultik.New),                         // 10. Vaultik orchestrator
 )
@@ -161,7 +161,7 @@ type Vaultik struct {
     Config          *config.Config
     DB              *database.DB
     Repositories    *database.Repositories
-    S3Client        *s3.Client
+    Storage         storage.Storer
     ScannerFactory  snapshot.ScannerFactory
     SnapshotManager *snapshot.SnapshotManager
     Shutdowner      fx.Shutdowner
@@ -341,12 +341,11 @@ CreateSnapshot(opts)
     └─► SnapshotManager.ExportSnapshotMetadata()
             │
             ├─► Copy database to temp file
-            ├─► Clean to only current snapshot data
-            ├─► Dump to SQL
-            ├─► Compress with zstd
+            ├─► Clean to only current snapshot data (VACUUM)
+            ├─► Compress binary SQLite with zstd
             ├─► Encrypt with age
-            ├─► Upload db.zst.age to S3
-            └─► Upload manifest.json.zst to S3
+            ├─► Upload db.zst.age to storage
+            └─► Upload manifest.json.zst to storage
 ```
 
 ## Deduplication Strategy
@@ -368,8 +367,8 @@ bucket/
 │
 └── metadata/
     └── {snapshot-id}/
-        ├── db.zst.age               # Encrypted database dump
-        └── manifest.json.zst        # Blob list (for verification)
+        ├── db.zst.age               # Encrypted binary SQLite database
+        └── manifest.json.zst        # Blob list (for pruning/verification)
 ```
 
 ## Thread Safety