Remove version field from metadata.json

- Removes noisy version mismatch warnings on every bd upgrade
- Version field in metadata.json was redundant with daemon version checking via RPC
- Daemon version mismatches still detected via HealthResponse
- Removes checkVersionMismatch() function and related test file
- Updates .beads/.gitignore to properly ignore merge artifacts

Amp-Thread-ID: https://ampcode.com/threads/T-7ba8aff2-97a0-4d0c-9008-e858bdfadd61
Co-authored-by: Amp <amp@ampcode.com>

cmd/bd/init.go

@@ -133,7 +133,7 @@ With --no-db: creates .beads/ directory and issues.jsonl file instead of SQLite
 			}
 
 			// Create metadata.json for --no-db mode
-			cfg := configfile.DefaultConfig(Version)
+			cfg := configfile.DefaultConfig()
 			if err := cfg.Save(localBeadsDir); err != nil {
 				fmt.Fprintf(os.Stderr, "Warning: failed to create metadata.json: %v\n", err)
 				// Non-fatal - continue anyway
@@ -256,7 +256,7 @@ bd.db
 
 	// Create metadata.json for database metadata
 	if useLocalBeads {
-		cfg := configfile.DefaultConfig(Version)
+		cfg := configfile.DefaultConfig()
 		if err := cfg.Save(localBeadsDir); err != nil {
 			fmt.Fprintf(os.Stderr, "Warning: failed to create metadata.json: %v\n", err)
 			// Non-fatal - continue anyway