fix(kiloclaw): skip destroyed instances in expiry sweep

[jeanduplessis]

Summary

• Exclude already-destroyed KiloClaw instances from subscription-expiry sweep candidates.
• Prevent repeated no-op expiry skip warnings for rows that no longer need enforcement.
• Add SQL-shape coverage so destroyed instances stay filtered at query time.

Verification

• N/A

Visual Changes

• N/A

Reviewer Notes

• Existing row-level destroyed-instance guard stays in place as defensive fallback.
• Targeted verification run in session:
  • pnpm --filter kiloclaw-billing test -- src/lifecycle.test.ts
  • pnpm --filter kiloclaw-billing typecheck