Refactor: Move Vaultik struct and methods to internal/vaultik package

- Created new internal/vaultik package with unified Vaultik struct
- Moved all command methods (snapshot, info, prune, verify) from CLI to vaultik package
- Implemented single constructor that handles crypto capabilities automatically
- Added CanDecrypt() method to check if decryption is available
- Updated all CLI commands to use the new vaultik.Vaultik struct
- Removed old fragmented App structs and WithCrypto wrapper
- Fixed context management - Vaultik now owns its context lifecycle
- Cleaned up package imports and dependencies

This creates a cleaner separation between CLI/Cobra code and business logic,
with all vaultik operations now centralized in the internal/vaultik package.

internal/cli/app.go

@@ -9,9 +9,13 @@ import (
 	"time"
 
 	"git.eeqj.de/sneak/vaultik/internal/config"
+	"git.eeqj.de/sneak/vaultik/internal/crypto"
 	"git.eeqj.de/sneak/vaultik/internal/database"
 	"git.eeqj.de/sneak/vaultik/internal/globals"
 	"git.eeqj.de/sneak/vaultik/internal/log"
+	"git.eeqj.de/sneak/vaultik/internal/s3"
+	"git.eeqj.de/sneak/vaultik/internal/snapshot"
+	"git.eeqj.de/sneak/vaultik/internal/vaultik"
 	"go.uber.org/fx"
 )
 
@@ -48,6 +52,10 @@ func NewApp(opts AppOptions) *fx.App {
 		config.Module,
 		database.Module,
 		log.Module,
+		s3.Module,
+		snapshot.Module,
+		crypto.Module, // This will provide crypto only if age_secret_key is configured
+		fx.Provide(vaultik.New),
 		fx.Invoke(setupGlobals),
 		fx.NopLogger,
 	}