Add repository traffic/insights tools (views, clones, referrers, paths)

### Describe the feature or problem you'd like to solve

The server has no way to read a repository's traffic/insights data. There are no tools wrapping the four traffic endpoints:

| Proposed tool | GitHub endpoint | Returns |
|---|---|---|
| `get_traffic_views` | `GET /repos/{owner}/{repo}/traffic/views` | Page views + unique visitors (14-day, daily or weekly) |
| `get_traffic_clones` | `GET /repos/{owner}/{repo}/traffic/clones` | Git clones + unique cloners (14-day, daily or weekly) |
| `get_traffic_referrers` | `GET /repos/{owner}/{repo}/traffic/popular/referrers` | Top 10 referring sites |
| `get_traffic_paths` | `GET /repos/{owner}/{repo}/traffic/popular/paths` | Top 10 most-visited paths |

Today an agent can read stars and forks but has no view into whether a repo is actually being visited or cloned, which is the primary signal for measuring adoption and reach of a project. This is a read-only capability.

### Proposed solution

Add the four tools above under the existing `repos` toolset, each `ReadOnlyHint: true`.

The implementation is thin because the pinned `go-github` client already exposes all four methods (`RepositoriesService.ListTrafficViews`, `ListTrafficClones`, `ListTrafficReferrers`, `ListTrafficPaths`), so no new HTTP plumbing is needed. The views/clones tools take an optional `per` parameter (`day` | `week`) mapping to `TrafficBreakdownOptions`; referrers/paths take just `owner`/`repo`.

One note on access: GitHub gates these endpoints behind push access to the repo (for GitHub Apps, the repository `Administration: Read` permission), so the tools should be annotated to require the `repo` scope rather than treated as public-read, even though the endpoints exist on public repos.

I'm happy to open a PR for this if the capability is something you'd accept.

### Example prompts or workflows (for tools/toolsets only)

1. "How many unique visitors and clones did `owner/repo` get in the last two weeks?"
2. "Where is traffic to my repo coming from? Show me the top referrers."
3. "Which pages/paths in `owner/repo` are people actually viewing?"
4. "Compare views vs. clones week over week for `owner/repo` and tell me if adoption is trending up."
5. "Build me a weekly adoption report for my repo: stars, forks, views, unique visitors, and clones." (traffic is the missing piece today; stars/forks are already covered)

### Additional context

Traffic data has a 14-day rolling retention window on GitHub's side, so these tools are especially useful to agents that snapshot the data on a schedule for longer-term trend tracking.

Start by reading the existing tools under the repos toolset and the pinned go-github methods ListTrafficViews, ListTrafficClones, ListTrafficReferrers, and ListTrafficPaths. Add the four read-only tools with the stated parameters and repo-scope requirement, then verify that views and clones accept day or week breakdowns while referrers and paths do not.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.