[FEATURE]: Add Contributor Expertise & Insights to Contributor Profile

## Feature Overview

Add a new **Contributor Expertise & Insights** section to the existing **Contributor Profile** page.

The current profile shows contribution statistics and history, but it mainly explains **what a contributor has done**. This feature would add a dynamic layer to help maintainers understand **what technical areas the contributor appears to specialize in** and **what meaningful patterns can be observed from their contributions**.

### 🧠 Areas of Expertise

Automatically identify the contributor's top **3–5 technical areas** from their Pull Requests and Issues.

Possible areas include:

* AI / Machine Learning
* Computer Vision
* Frontend / UI
* Backend
* APIs
* Testing
* CI/CD
* Documentation
* Security
* Search / Embeddings

The expertise should be **dynamic and contributor-specific**, with levels such as **HIGH, MEDIUM, or LOW** based on available contribution evidence.

For example:

* **AI / Machine Learning — HIGH**
* **Computer Vision — HIGH**
* **Search / Embeddings — MEDIUM**
* **Testing — MEDIUM**

### 💡 Contribution Insights

Display a few short, meaningful observations based on the contributor's contribution patterns.

Examples:

* Strong focus on AI/ML and Computer Vision.
* Frequently contributes to feature development.
* Contributions are concentrated in a particular repository.
* Recent contribution activity is consistent.

Insights should be **generated from actual contribution data**, not hardcoded.

### 🔄 Reporting Window

Expertise and Insights should respect the existing **Reporting Window & Date Presets**:

* Last Week
* Last 30 Days
* Last 1 Year
* All Time
* Custom Date Range

Changing the timeframe should update the analysis based on contributions within the selected period.

### 📍 Proposed Placement

Place the new section below the existing **Contribution Summary** and above **Contribution Velocity Over Time**.

**Reporting Window → Contribution Summary → 🧠 Expertise & Insights → Contribution Velocity → PRs / Issues →Footer**

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## Additional Context

The feature is intended to help maintainers understand a contributor at a glance without manually reviewing their complete contribution history.

The proposed UI can contain two responsive cards:

**🧠 Areas of Expertise**

* AI / Machine Learning — **HIGH**
* Computer Vision — **HIGH**
* Testing — **MEDIUM**

**💡 Contribution Insights**

* Strong focus on AI/ML.
* Feature-oriented contributions.
* Recent activity is consistent.

The implementation should reuse existing contributor data where possible and avoid unnecessary GitHub API requests.

If there is insufficient data to determine reliable expertise or insights, display a clear **insufficient-data state** instead of making unsupported assumptions.

The feature should **complement existing statistics rather than duplicate them**.

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## Code of Conduct

* [x] I have joined the [Discord server](https://discord.gg/hjUhu33uAn) and will post updates there
* [x] I have searched existing issues to avoid duplicates

Start by tracing the existing Contributor Profile, Contribution Summary, and Reporting Window/date-preset data flow, including how Pull Requests and Issues are already loaded. Done means the new responsive Expertise and Insights cards update for each selected timeframe, reuse existing data where possible, and show an insufficient-data state when evidence is limited.

索引モデルが issue の本文から書いたものです。