Release StrataGate DSH 0.2.16

[diqierjia]

Summary

• isolate open tails, block sealing, decay, and automatic block context per DSH session
• keep Events and Elements project-scoped for cross-session recall
• migrate SQLite storage to schema v5 with optional thread ownership
• make English README.md the unambiguous npm landing page while retaining packaged Chinese docs
• add foundational and differentiating npm discovery keywords

Verification

• npm run check
• npm test (75 tests)
• npm run build
• npm run verify:dsh
• npm publish --workspace stratagate-dsh --dry-run --json