devops: graph limit accepts a 101st root graph

## Description

`AddGraphInfo` checks `s.totalGraphNum > maxGraphNum` before incrementing the counter. With `maxGraphNum` set to 100, calls 1 through 101 therefore succeed, and the error is returned only for call 102.

## Reproduction

On current `main` (`6752ff8da9b1ea85c8e91b27b0a64fef099f22f9`):

1. Create a fresh container service.
2. Call `AddGraphInfo` 100 times with non-nil empty graph info; all calls succeed.
3. Call it a 101st time.

The 101st call succeeds and `totalGraphNum` becomes 101, despite the error text advertising `max=100`.

## Expected behavior

The 101st root graph should be rejected, leaving the counter and container unchanged at 100 root graphs.

## Suggested fix

Use `>=` for the pre-increment limit check and add a boundary regression test covering calls 100 and 101.

Start by locating AddGraphInfo and its pre-increment maxGraphNum check on current main at commit 6752ff8da9b1ea85c8e91b27b0a64fef099f22f. Run or add a boundary regression test covering calls 100 and 101; done means the 100th call succeeds, the 101st is rejected, and the counter and container remain unchanged at 100.

Written by the indexing model from the issue text.