office: replay TurtleTerm operator flows on current main

[mdheller]

Summary

Clean replay of the office operator surface from stale PR #4 onto current main.

This preserves the original office payload while avoiding overwrite of the 80 intervening commits that landed on main after the stale branch diverged.

Changes

• Adds turtle-term office plan.
• Adds /office plan alias support.
• Adds turtle-term office evidence inspect <path>.
• Emits operator-plan JSON with:
  • sourceos.turtleterm.office.operator_plan.v0
  • command_argv for sourceosctl office ...
  • receipt_command for turtle-term run -- sourceosctl office ...
  • expected office runtime contract kinds.
• Emits evidence-summary JSON with:
  • sourceos.turtleterm.office.evidence_summary.v0
  • office document/version/writeback IDs when present.
• Adds smoke coverage while preserving current main agent-status smoke tests.
• Updates README and install validation docs.

Boundary

No Google/Microsoft/Apple runtime dependency is introduced. TurtleTerm remains an operator/receipt surface and does not become the office runtime, WOPI host, or document engine.

Replay discipline

The original PR #4 branch was 80 commits behind current main and touched files that have since moved forward. This replay ports only the office payload and intentionally excludes stale packaging/workflow churn.

Validation target

make turtle-smoke

The smoke target runs assets/sourceos/tests/test_sourceos_term_smoke.py and syntax checks packaging helpers.