#1333 Add a :micdrop: emoji / reaction shortcode (swamp-native art included)

Problem

There's no 🎤 shortcode. It is the natural reaction after a clean swamp extension push clears the adversarial-review gate on the first try, and right now there's nothing to express it with. Related to #64 (reactions + Giphy in comments) — a named 🎤 would be a great charter member of that set.

Proposed solution

Add a mic-drop to the emoji / reaction shortcode set. Swamp-themed art already exists — dropping a candidate here:

A Discord/emoji-sized companion (128×128, transparent, still legible at 32px, swamp-slime palette with a dead-face x x mic) is here for the reaction-set use case, where the full illustration above is too detailed to read small:

Both live in https://github.com/sntxrr/swamp-assets (MIT-friendly, take/edit freely); the emoji has a reproducible Pillow generator alongside it.

Alternatives considered

• Ship a plain 🎤⬇️ pairing — works, but no swamp character.
• Use only the full mascot illustration — great for a banner or repo hero, but it turns to mush at emoji/reaction size, hence the flat 128px companion.