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/codex_test.go

@@ -35,6 +35,7 @@ type codexFixture struct {
 func prepareCodexFixture(t *testing.T, existingRaw string) *codexFixture {
 	t.Helper()
 	homeDir := filepath.Join(t.TempDir(), "home with 'quote %ELYDORA_HOOK_PATH%")
+	preparePrivateTransactionTestDirectory(t, homeDir)
 	agentDir := filepath.Join(homeDir, ".elydora", codexTestAgentID)
 	configPath := filepath.Join(homeDir, ".codex", "hooks.json")
 	guardPath := filepath.Join(agentDir, "guard.js")