fix(workspace): preserve adopted sessions in StrictMode

[decode2]

Linked issue

Closes #62

• Approved issue linked.

Pull request type

• Bug fix (type:bug)

Summary

• Distinguishes backend-owned adopted PTYs from view-owned terminals.
• Prevents StrictMode replay from spawning, killing, or generically restarting adopted sessions.

Test plan

• TerminalView focused suite: 45/45.
• Lint, typecheck, build passed.
• Existing ordinary terminal lifecycle coverage remains green.

Chained pull request context

• Previous PR: feat(workspace): add lifecycle switcher #61
• Next PR: PR12c2 output broker
• Review this PR first: StrictMode ownership boundary
• Intentionally out of scope: buffering, binding authority, async restart disposal

Contributor checklist

• Duplicate search and approved issue
• Exactly one type label
• Reproducible evidence
• Conventional commit; no AI attribution