fix(security): restrict subscription page access to /{uuid}/sub, fix multi-user rendering & inject vars into wrangler.toml in CI

[ukari]

Description

This PR addresses a security vulnerability and a logical bug in the subscription page handling:

1. Security Fix: Removed the unauthenticated global /sub endpoint. The subscription page now requires the UUID in the URL path (e.g., /${uuid}/sub) to prevent unauthorized access to sensitive configuration details (Information Disclosure).
2. Logic Fix: Refactored src/pages/index.ts to render the specific configuration matching the UUID in the request URL. Previously, the UI hardcoded to always display the first UUID in the environment variable, ignoring other users.
3. Refactor: Extracted HTML generation logic into subscriptionPageTextMaker for better readability.
4. CI: inject GitHub vars into wrangler.toml for UUID/PROXY_IP.

Related Issue

Fixes security vulnerability where /sub exposed credentials without authentication.
Also fixes the issue where multi-UUID setups only displayed the first user's config.

Motivation and Context

Security Risk: The previous /sub endpoint allowed anyone knowing the domain to view the VLESS UUID and connection details, bypassing the proxy's authentication. By enforcing /${uuid}/sub, the UUID acts as a pre-shared key for access.

Bug: For users employing multiple UUIDs (e.g., UUID=id1,id2), accessing the subscription page previously would always show the config for id1, even if the intended user was id2. This PR ensures id2 sees their own config.

Align Document & Deploy Behavior: According to README.md and wrangler.toml it might should be able to sync repository variables for PROXY_IP/UUID to Cloudflare Worker Pages instance in PLAINTEXT for section Variables and Secrets when deploy in Method 3: GitHub Actions

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.