Refresh documentation for v0.2.3

docs/platforms.md

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+# Platform notes
+
+Cassady is a terminal CLI. Most behavior is shared across platforms, but environment-variable syntax, paths, and terminal behavior differ.
+
+## macOS and Linux
+
+Set an API key for the current shell:
+
+```sh
+export OPENAI_API_KEY=...
+cass check
+cass
+```
+
+Use normal POSIX paths:
+
+```sh
+cass --cwd /Users/alex/project
+cass --cwd /home/alex/project
+```
+
+Shell tools run through `sh -c` from the launch cwd.
+
+## Windows
+
+Release builds include a Windows x86_64 binary. Use PowerShell syntax for environment variables:
+
+```powershell
+$env:OPENAI_API_KEY = "..."
+cass check
+cass
+```
+
+Example path usage:
+
+```powershell
+cass --cwd C:\Users\alex\project
+```
+
+Current docs and examples are primarily terminal-CLI oriented. Deeper Windows polish for terminal behavior, path handling, shell behavior, filesystem edge cases, and release usability is planned for a later release. Avoid assuming every Windows path or shell edge case is polished in the current version.
+
+## Config location
+
+Cassady currently stores config under the home directory at:
+
+```text
+~/.cass
+```
+
+That directory contains `config.json`, `providers.json`, `models.json`, `global.md`, `conversations/`, and installed bundled docs.
+
+## Non-interactive contexts
+
+- `cass check` is suitable for scripts and CI because it prints text and exits non-zero on errors.
+- `cass setup` requires an interactive terminal.
+- `cass` chat is an interactive terminal UI.
+
+## Release artifacts
+
+When using release archives, each archive contains both `cass` and `cassady`. Put the extracted binaries somewhere on your `PATH` or run them by explicit path. Cassady itself does not install, update, or manage PATH entries.