Rewrite README for game storytellers

[is2b007]

Summary

• rewrite the README from the perspective of a narrative writer or indie game maker
• explain Reed's complete workflow: story structure, graph authoring, cast, variables, playtesting, validation, localization, voice production, history, GitHub collaboration, MCP, and game exports
• add direct v0.1.9 download links for macOS, Windows, and Android
• align the Android package version with Reed 0.1.9

Why

The previous README documented the architecture and individual integrations, but it did not clearly show what a writer can accomplish from the first beat through localization, recording, and engine handoff. It also offered no complete cross-platform release download section.

Verification

• Android unit tests passed with JDK 21
• Android lint passed
• Android debug APK assembled successfully
• APK signature verification passed (Android debug certificate, v2 signature)
• APK manifest reports version code 9, version name 0.1.9, min SDK 33, and target SDK 36
• git diff --check
• existing macOS DMG/ZIP and Windows x64 ZIP previously passed archive, native-binary, signature, and launch checks

Release assets after merge

• Reed-0.1.9-arm64.dmg
• Reed-darwin-arm64-0.1.9.zip
• Reed-win32-x64-0.1.9.zip
• Reed-android-0.1.9-debug.apk
• SHA256SUMS-0.1.9.txt