feat(go): durable transaction engine and Kiro IDE 1.0 adapter

Split the monolithic transaction into focused modules: append-only
crash-recoverable journal under ~/.elydora/transactions with owner
tokens and per-transaction namespaces, staged atomic publication
(stage .pending, fsync, rename, fsync), platform-specific atomic
replacement (MoveFileEx, renameat2, renamex_np), private-directory
hardening per OS, lock-guarded recovery, and workspace cleanup that
removes only transaction-created empty directories.

Add the Kiro IDE 1.0 plugin: strict v1 hook schema with one enabled
PreToolUse guard and PostToolUse audit pair bound to the active
workspace, agent-to-workspace identity binding in runtime config, and
exact migration of the legacy elydora-audit.kiro.hook contract.

Gates: go test ./... and -race pass, go vet clean, govulncheck reports
zero reachable vulnerabilities, git diff --check clean.

cmd/elydora/plugins/transaction_identity_darwin.go

@@ -0,0 +1,17 @@
+//go:build darwin
+
+package plugins
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+)
+
+func transactionFileIdentity(_ *os.File, info os.FileInfo) (string, error) {
+	stat, ok := info.Sys().(*syscall.Stat_t)
+	if !ok {
+		return "", fmt.Errorf("macOS file identity is unavailable")
+	}
+	return fmt.Sprintf("%x:%x", uint64(stat.Dev), stat.Ino), nil
+}