feat(m365): add calendar copilot approvals

[sudie-codes]

Summary

• add calendar agenda, free/busy, and queued change tools under extensions/m365/src/calendar
• canonicalize change plans with plan hashes and exact-once TaskFlow approvals
• re-check attendee availability and event change keys before applying approved mutations

Notes

• This is PR 2 of 3 and is stacked on codex/m365-outlook-triage.
• Writes stay approval-gated for create, update, cancel, and reschedule.
• Ambiguous natural-language times are rejected before any write plan is queued.

Testing

• pnpm test extensions/m365/src/config.test.ts extensions/m365/src/graph-client.test.ts extensions/m365/src/runtime-common.test.ts extensions/m365/src/calendar/plan.test.ts extensions/m365/src/calendar/graph.test.ts extensions/m365/src/calendar/tool.test.ts extensions/m365/src/tools-v2.test.ts extensions/m365/src/approval-actions.test.ts
• pnpm exec oxlint extensions/m365/index.ts extensions/m365/openclaw.plugin.json extensions/m365/src/config.ts extensions/m365/src/config.test.ts extensions/m365/src/graph-client.ts extensions/m365/src/graph-client.test.ts extensions/m365/src/runtime-common.ts extensions/m365/src/runtime-common.test.ts extensions/m365/src/calendar/plan.ts extensions/m365/src/calendar/plan.test.ts extensions/m365/src/calendar/graph.ts extensions/m365/src/calendar/graph.test.ts extensions/m365/src/calendar/tool.ts extensions/m365/src/calendar/tool.test.ts extensions/m365/src/calendar/types.ts extensions/m365/src/tools-v2.ts extensions/m365/src/tools-v2.test.ts extensions/m365/src/approval-actions.ts extensions/m365/src/approval-actions.test.ts

Known Baseline Follow-up

• Repo-wide pnpm build remains blocked by unrelated latest-main type/export drift already present above this stacked PR.