docs(cursor): fix leftover OpenCode references in cursor template

[msdjzmst]

Summary

The cursor agent-type template still refers to "OpenCode" in three user-facing strings — these are leftovers from the initial copy of opencode/template.md when cursor support landed in #189 (feat/cursor-type). The delivery-mode constraint they describe (no Monitor tool, only turn/off) is correct for cursor as declared in scripts/drivers/types/cursor/type.conf (monitor=no, delivery_modes=turn off), but the agent name was never renamed.

This PR renames OpenCode → Cursor CLI in those three strings, matching the naming convention used by other CLI-only types (e.g. Copilot CLI in copilot's template).

What changes

Three string substitutions in scripts/drivers/types/cursor/template.md:

line	context
61	delivery-mode picker footnote
109	actas confirmation message
122	mode set rejection message

No behavior change — pure user-facing string fix.

Verification

Confirmed against v1.1.7 tag and main:

$ curl -s https://raw.githubusercontent.com/fujibee/agmsg/v1.1.7/scripts/drivers/types/cursor/template.md | grep -n OpenCode
61:     - OpenCode has no Monitor tool, so `monitor` and `both` modes are not offered here.
109:5. Tell the user: "Now acting as `<name>`. Sends will use `<name>` as the from agent. (OpenCode has no Monitor tool, so receive still covers all of your registered roles in this project.)"
122:1. Parse the mode. OpenCode supports only `turn` and `off` — reject `monitor` and `both` with: "OpenCode has no Monitor tool; only `turn` or `off` modes are supported."

Follow-up (out of scope for this PR)

While investigating I noticed scripts/drivers/types/antigravity/template.md has an analogous copy-paste issue (three strings referring to Codex where they should refer to Antigravity). It also appears to conflict with antigravity's type.conf which declares delivery_modes=monitor turn both off, so the correct fix isn't just a rename — the whole "no Monitor tool" section may not belong there. Happy to file a separate issue if useful.

Test plan

• grep -c OpenCode scripts/drivers/types/cursor/template.md → 0
• grep -c "Cursor CLI" scripts/drivers/types/cursor/template.md → 3
• Full-file diff reviewed: only the three intended lines changed