docs(ms-teams): add M365 tenant + active Azure subscription to Teams prerequisites (EN+ZH)

[FelixLin6]

Why

The Microsoft Teams deployment entry never stated that creating the Azure Bot resource (Step 1) requires an active Azure subscription — and that an Azure subscription is not the same as a Microsoft 365 account. The general prerequisites section ("you don't need developer accounts / technical knowledge") only fits Telegram/Lark. A customer was blocked at Step 1: they had an M365 account but no Azure subscription, and the docs didn't say they needed one.

What

Adds a Prerequisites block to the Microsoft Teams entry of the deployment guide, leading with the two genuine prerequisites:

1. A Microsoft 365 organization (work/school) tenant with Teams (not a personal Microsoft account).
2. An active Azure subscription — required to create the Azure Bot resource even on the Free (F0) tier, with an explicit "M365 account ≠ Azure subscription" clarification + a link to create a free subscription.

Plus a tip clarifying that "free Azure tier" = the F0 bot pricing, which still has to live inside a subscription.

Scope

• Microsoft Teams entry only (no other channel touched).
• Applied to both EN (docs/getting-started/channel-deployment.md, Option G) and ZH (docs/zh/getting-started/channel-deployment.md, 选项H).
• 2 files, +22 lines, docs-only.

🤖 Generated with Claude Code

[FelixLin6]

Closing — the Microsoft Teams deployment-guide rework will be handled by Eric He, who will rework the guide flow holistically. This PR's content (the missing prerequisites: an active Azure subscription + a Microsoft 365 organization tenant, EN+ZH, with the 'M365 account ≠ Azure subscription' clarification) is preserved here and on branch docs/ms-teams-prereqs for reference/incorporation. Motivating issue: a customer was blocked at Azure Bot creation (Step 1) because the docs never stated an Azure subscription was required.