[feature]: Automatic PII Detection and Masking in Mocks and Test Cases

### 👀 Is there an existing feature request for this?

- [x] I have searched the existing issues

### 🔖 Enhancement description

## Problem Statement

Keploy records real API calls, database queries, and external dependencies from user traffic to generate test cases and mocks. This real data often contains **Personally Identifiable Information (PII)** such as:
- Emails (e.g., `john.doe@example.com`)
- IP addresses
- Phone numbers
- Credit card numbers
- Names, addresses, or other sensitive fields

When these mocks and test cases are:
- Committed to Git repositories
- Shared across teams or environments
- Used in CI/CD pipelines

...there is a risk of unintentionally exposing real user PII, leading to privacy breaches and non-compliance with regulations like **GDPR**, CCPA, HIPAA, etc.

While Keploy has a `keploy sanitize` command (implemented in `cli/sanitize.go`), it currently focuses on basic secret removal. Enhancing it with comprehensive PII detection and configurable masking would significantly improve security and make Keploy safer for enterprise adoption.

### 🎤 Why should this be worked on?

- Prevents accidental PII leaks in shared mocks/tests.
- Minimal overhead (regex-based, no heavy dependencies initially).

### 💻 Repository

keploy

Start with cli/sanitize.go to understand the existing secret-removal behavior and how sanitize is invoked. Define the supported PII categories, masking configuration, and expected handling for recorded mocks and test cases; done means the agreed PII data is detected and masked without exposing real values.

Written by the indexing model from the issue text.