Add Discord badge with live member count to README

[themuffinator]

Motivation

• Surface project community presence by showing a live Discord member count in the repository header.
• Provide a direct invite link to the project's Discord server for easier contributor and user onboarding.
• Keep the README header consistent with existing shields-style metadata already present in the file.

Description

• Updated README.md to add a Discord badge to the centered badge row using the shields.io Discord endpoint.
• The badge uses the server numeric ID 1305498944247435356 via https://img.shields.io/discord/1305498944247435356?label=Discord&logo=discord&logoColor=white.
• Wrapped the badge in a link to the project invite at https://discord.gg/T32mFejwR4 and preserved the existing <p align="center"> layout.

Testing

• No automated tests were run because this is a documentation-only change.
• The file update was applied to README.md and committed successfully.

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Codex Task