Improve setup script and enhance documentation

[NilsSei]

Summary

• Add libsecret dependency to fix keytar build issues on Termux
• Replace pkg list-installed with dpkg -s for more reliable package checking
• Enhance README with prerequisites, troubleshooting guide, and verification steps
• Add detailed installation instructions and usage guide
• Include comprehensive "What Gets Installed" section for transparency

Changes Made

setup.sh

• Added libsecret package installation to resolve keytar native module build failures
• Changed package check from pkg list-installed to dpkg -s for better reliability
• Updated installation summary to include libsecret

README.md

• Added Prerequisites section with clear requirements
• Expanded installation instructions with step-by-step commands
• Added Usage section with authentication steps
• Added Verification section to help users confirm successful installation
• Added Troubleshooting section with common issues and solutions
• Added "What Gets Installed" section listing all packages and modules

Testing

• Tested on Termux environment
• Verified keytar builds successfully with libsecret
• Confirmed dpkg check works correctly for package verification

[Devon-Scott]

I just want to thank you as this update fixed the install on my Galaxy Tab S10+. Sharp still didn't seem to work, but everything else did. Is there a reason you haven't merged this yet?

[tom9358]

With this update I still get failure to install keytar, which I also get with the original script:

gyp info spawn args ]
Using overrides found in /data/data/com.termux/files/home/.gyp/include.gypi
Package libsecret-1 was not found in the pkg-config search path.
Perhaps you should add the directory containing libsecret-1.pc' to the PKG_CONFIG_PATH environment variable No package 'libsecret-1' found gyp: Call to 'pkg-config --cflags libsecret-1' returned exit status 1 while in binding.gyp. while trying to load binding.gyp gyp ERR! configure error gyp ERR! stack Error: gyp` failed with exit code: 1
gyp ERR! stack at ChildProcess. (/data/data/com.termux/files/usr/lib/node_modules/npm/node_modules/node-gyp/lib/configure.js:317:18)
gyp ERR! stack at ChildProcess.emit (node:events:509:20)
gyp ERR! stack at ChildProcess._handle.onexit (node:internal/child_process:294:12)
gyp ERR! System Linux 5.4.254-qgki-28575149-abA528BXXSBGYI3
gyp ERR! command "/data/data/com.termux/files/usr/bin/node" "/data/data/com.termux/files/usr/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js" "rebuild"
gyp ERR! cwd /data/data/com.termux/files/usr/lib/node_modules/@github/copilot/node_modules/keytar
gyp ERR! node -v v26.2.0
gyp ERR! node-gyp -v v12.3.0
gyp ERR! $npm_package_name keytar
gyp ERR! $npm_package_version 7.9.0
gyp ERR! not ok
✗ Failed to compile keytar