release(v2.0.0): cross-platform release — Linux/macOS/Windows/WSL

Creates full release package with:
- release/install.sh (universal cross-platform installer)
- release/windows/install.bat (Git Bash/MSYS2)
- release/windows/install.ps1 (PowerShell)
- release/homebrew/gyandoot.rb (Homebrew formula)
- release/archives/ prebuilt binary archives
- release/README.md (platform-specific install guide)
- install.sh updated with same cross-platform logic
- README.md updated

release/homebrew/gyandoot.rb

@@ -0,0 +1,49 @@
+# typed: true
+# frozen_string_literal: true
+
+# GyanDoot v2.0 — Homebrew Formula
+# Usage:
+#   brew tap gnpl_admin/gyandoot
+#   brew install gyandoot
+#
+# For the latest version, run:
+#   brew upgrade gyandoot
+
+class Gyandoot < Formula
+  desc "GyanDoot — AI Agent Platform: search, browse, and automate"
+  homepage "https://git.gyannetra.in/gnpl_admin/gyandoot-v2"
+  url "https://git.gyannetra.in/gnpl_admin/gyandoot-v2.git",
+      tag:      "v2.0.0",
+      revision: "3b5b995fcec8f11bdb9d7e0fb24c50f20c2d9d38"
+  license "MIT"
+  head "https://git.gyannetra.in/gnpl_admin/gyandoot-v2.git", branch: "main"
+
+  depends_on "rust" => :build
+  depends_on "node" => :recommended
+
+  def install
+    system "cargo", "install", "--locked", "--root", prefix,
+           "--path", "."
+
+    # Generate shell completions
+    bash_completion.install "completions/gyandoot.bash" => "gyandoot"
+    zsh_completion.install "completions/gyandoot.zsh" => "_gyandoot"
+    fish_completion.install "completions/gyandoot.fish" => "gyandoot.fish"
+  end
+
+  def post_install
+    ohai "GyanDoot installed! Quick start:"
+    puts "  gyandoot setup    # Configure LLM provider"
+    puts "  gyandoot run      # Start interactive agent"
+    puts ""
+    ohai "Optional — Install Camoufox Browser for web search:"
+    puts "  npx --yes camoufox-js@0.11.0 fetch"
+    puts ""
+    ohai "macOS Gatekeeper fix (required on Apple Silicon):"
+    puts "  xattr -dr com.apple.quarantine ~/Library/Caches/camoufox"
+  end
+
+  test do
+    assert_match "GyanDoot", shell_output("#{bin}/gyandoot --version")
+  end
+end