Use native ARM64 runners instead of cross-compilation

Fix cross-compilation cache issues with separate cache key

Add Linux aarch64 (ARM64) release binaries

Update README: make Telegram optional, consolidate setup sections

Fix code formatting

Add notification relay and custom message support

Make Telegram config optional when other messengers are configured

Add interactive installation script

Add Discord and Signal messenger support with abstraction layer

Fix hook not responding with multiple concurrent requests

Fix Linux musl build and clippy errors

Fix Rust formatting errors

Remove accidentally committed pycache files

Restructure: promote Rust to root, archive Python

Add Rust implementation for smaller binaries (~4MB vs 50MB)