Add a formula for installing the share CLI

Lets `brew install share` pull the versioned release archive from the
share repository's Gitea releases instead of building from source.

README.md

@@ -1,6 +1,6 @@
 # TZGyn Homebrew Tap
 
-Casks for TZGyn apps. Hosted on Gitea — the full URL is required when tapping.
+Casks and command-line formulae for TZGyn apps. Hosted on Gitea — the full URL is required when tapping.
 
 ## Install
 
@@ -13,6 +13,32 @@ brew install --cask kapture
 Homebrew may print an "Unsupported tap" warning for non-GitHub taps — it's
 harmless.
 
+## Formulae
+
+### share
+
+BitTorrent-style swarm file sharing CLI. A single binary serves as the client
+(`send`/receive), the background daemon, and the relay:
+
+```bash
+brew install share
+```
+
+Seed a file into a new room (prints a room code):
+
+```bash
+share send file.txt
+```
+
+On the other machine, join that room — everyone in it both sends and receives:
+
+```bash
+share <code>
+```
+
+Releases carry macOS (Apple Silicon and Intel) and Linux builds; the formula
+currently installs the Apple Silicon build.
+
 ## Casks
 
 ### kapture
@@ -29,6 +55,6 @@ Menu bar screenshot app with on-device OCR:
 
 ## Releases
 
-Releases are published to each app's GitHub repository as zips attached to
+Releases are published to each app's Gitea repository as zips attached to
 version tags; the casks in this tap point at the latest release. Releases are
 notarized (Developer ID + stapled ticket).