## Why
Managed requirements can already centrally disable apps, but they could
not express the per-tool app approval rules that normal config already
supports. That left admins without a way to enforce connector tool
approvals through `/etc/codex/requirements.toml` or cloud requirements.
## What changed
- Extend app requirements with per-tool `approval_mode` entries.
- Merge managed app tool requirements across managed sources while
preserving higher-precedence exact tool settings.
- Apply managed tool approvals separately from user app config so
managed policy is matched only on raw MCP `tool.name`, while user config
keeps the existing raw-name-then-title convenience fallback.
- Add coverage for local requirements, cloud requirements parsing,
managed-over-user precedence, and a title-collision case that must not
widen managed auto-approval.
## Configuration shape
Local `/etc/codex/requirements.toml` and cloud requirements use the same
TOML shape:
```toml
[apps.connector_123123.tools."calendar/list_events"]
approval_mode = "approve"
```
This is a per-tool approval rule keyed by app ID and raw MCP tool name,
not an app-level boolean such as `apps.connector_123123.approve = true`.
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