docs: correct Teams/Outlook channel disposition (LIA-392)

[sliamh11]

Summary

• The prior cleanup audit claimed Teams and Outlook had "zero router instantiation." False — both are fully wired (channels/index.ts imports them, index.ts's registry loop instantiates every registered factory, router.ts dispatches via ownsJid()) and unit-tested, just not proven end-to-end against real Azure Bot Framework / Microsoft Graph (this environment has no credentials to run that).
• README.md: adds Teams/Outlook to the channel list and comparison-table count (5 → 7).
• AGENTS.md: extends the channel-architecture bullet with an explicit readiness caveat rather than either omitting them or silently claiming production-readiness.

Full corrected disposition + acceptance-criteria mapping recorded in a Linear comment on LIA-392. Issue stays open pending a future session with real credentials to complete the E2E acceptance criterion.

Test plan

• git diff --stat — exactly 2 files, README.md + AGENTS.md
• Wiring claim grep-confirmed (src/channels/index.ts, src/index.ts, src/router.ts)
• Both provider unit test suites pass: Teams 9/9, Outlook 10/10
• Confirmed both test suites mock all external SDKs (no live E2E exists) — the "not yet proven end-to-end" claim is accurate, not underclaimed
• Native code-reviewer + GPT + GLM co-gate — all SHIP
• verification-gate — SHIP

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