fix(android): AGP 8 / Gradle 8 support — drop deprecated 'maven' plugin, keep com.reactlibrary namespace, set default SDKs, widen peerDeps, update README

[ahmed-gelemli]

Problem

Android builds on modern toolchains (Gradle 7/8, AGP 8) fail with:

• Plugin with id 'maven' not found
• compileSdkVersion is not specified
• namespace not specified for project ...

The package also still referenced jcenter() and documented the obsolete installArchives flow. Additionally, current Expo / RN templates (React 19) could not install the package because of a too‑narrow react peerDependency (<19.0.0).

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What this PR does

Android / Gradle

• Removes the deprecated maven plugin and all legacy publishing tasks.
• Adds an Android namespace but keeps it as com.reactlibrary to remain fully backward‑compatible with the existing Java package and RN autolinking.
• Provides sane default SDK versions (still overrideable from the host app via rootProject.ext):
  • compileSdkVersion: 34
  • targetSdkVersion: 34
  • minSdkVersion: 21
• Drops jcenter().
• Modernizes lint {} and Java 8 compileOptions.

Peer deps

• Widens react to allow React 19: >=16.8.0 <20.0.0
• Normalizes react-native range to >=0.59.0 <1.0.0
• Widens react-native-svg to >=9.5.3 <17.0.0 so modern Expo/RN stacks don’t fail to install.

Docs

• Updates android/README.md to remove the obsolete installArchives / maven instructions and mention maven-publish as the modern alternative if Gradle publishing is still desired.

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Backwards compatibility

• No Java package renames; we explicitly kept com.reactlibrary.
• Apps that already define their own SDK versions via rootProject.ext continue to work.
• The peer dep widening only removes installation friction; there are no runtime changes.

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How to test

1. Install this branch in a modern Expo / RN app (React 18/19 both work):

   # package.json
   "@iconscout/react-native-unicons": “github:ahmed-gelemli/react-native-unicons#a3f0792"

[ahmed-gelemli]

@tarunmangukiya @rankarpan @imzedi gentle ping — this PR is comprehensive & non‑breaking, fixes Gradle 7/8 + AGP 8 build failures, and widens peer deps for React 19. Details are in the description. Could we get a quick review/merge + release? 🙏