Add exclude patterns, snapshot prune, and other improvements

- Implement exclude patterns with anchored pattern support:
  - Patterns starting with / only match from root of source dir
  - Unanchored patterns match anywhere in path
  - Support for glob patterns (*.log, .*, **/*.pack)
  - Directory patterns skip entire subtrees
  - Add gobwas/glob dependency for pattern matching
  - Add 16 comprehensive tests for exclude functionality

- Add snapshot prune command to clean orphaned data:
  - Removes incomplete snapshots from database
  - Cleans orphaned files, chunks, and blobs
  - Runs automatically at backup start for consistency

- Add snapshot remove command for deleting snapshots

- Add VAULTIK_AGE_SECRET_KEY environment variable support

- Fix duplicate fx module provider in restore command

- Change snapshot ID format to hostname_YYYY-MM-DDTHH:MM:SSZ

Makefile

@@ -59,4 +59,8 @@ test-coverage:
 
 # Run integration tests
 test-integration:
-	go test -v -tags=integration ./...
+	go test -v -tags=integration ./...
+
+local:
+	VAULTIK_CONFIG=$(HOME)/etc/vaultik/config.yml ./vaultik snapshot --debug list 2>&1
+	VAULTIK_CONFIG=$(HOME)/etc/vaultik/config.yml ./vaultik snapshot --debug create 2>&1