Add microsoft-365-copilot (new cask)

[AdamBaali]

---

After making any changes to a cask, existing or new, verify:

• The submission is for a stable version or documented exception.
• brew audit --cask --online <cask> is error-free.
• brew style --fix <cask> reports no offenses.

Additionally, if adding a new cask:

• Named the cask according to the token reference.
• Checked the cask was not already refused (add your cask's name to the end of the search field).
• brew audit --cask --new <cask> worked successfully.
• HOMEBREW_NO_INSTALL_FROM_API=1 brew install --cask <cask> worked successfully.
• brew uninstall --cask <cask> worked successfully.

---

• AI was used to generate or assist with generating this PR. Please specify below how you used AI to help you, and what steps you have taken to manually verify the changes, including zap stanza paths.

AI (Claude) helped scaffold this cask; I verified everything manually. The download
resolves through Microsoft's fwlink (linkid=2325438) to the versioned installer on
res.cdn.office.net; I computed the sha256 from that file and read the pkg receipt
(com.microsoft.m365copilot) with pkgutil --expand-full. The installer bundles
Microsoft AutoUpdate, which is shared across Microsoft apps, so the cask declares
depends_on cask: "microsoft-auto-update" and uninstall forgets only Copilot's own
receipt — a normal brew uninstall leaves AutoUpdate in place for Office, Teams, etc.,
with AutoUpdate's teardown owned by the microsoft-auto-update cask. brew audit --cask --online --new and brew style pass; I installed and uninstalled locally and
confirmed AutoUpdate remained. The zap paths under com.microsoft.m365copilot were
confirmed against ~/Library.

---