docs(website): reconcile installation docs with v0.2.0 shipped reality

installation.md predated the install/packaging work that landed on main:
- drop the "once published" placeholders now that v0.2.0 is live
- fix the Homebrew/Scoop commands (tap/bucket-add forms; the bare
  `brew install rdbms-playground` was wrong)
- add the curl|sh and PowerShell one-line installers (ADR-0055),
  `cargo install` / `cargo binstall` (ADR-0056), and prebuilt binaries
- present winget as coming-soon (PR awaiting the public catalogue)

command-line-options.md: add `-V`/`--version` and the in-app `version`
command (ADR-0054).

website/src/content/docs/using-the-playground/command-line-options.md

@@ -29,8 +29,13 @@ rdbms-playground path/to/project
 | `--no-undo` | Disable the undo machinery for this run — no snapshot is taken before each change (see [Undo, redo & history](/using-the-playground/undo-and-history/)). |
 | `--demo` | Turn on demonstration mode — a teaching aid that briefly shows an on-screen badge for keys that otherwise leave no visible mark (Tab, Enter, the arrows, and the like). Useful for screencasts and for demonstrating the playground to a class. Off by default. |
 | `--log-file <PATH>` | Write diagnostic logging to `PATH`. |
+| `-V`, `--version` | Print the version and exit. |
 | `-h`, `--help` | Print the usage banner and exit. |
 
+Once the playground is running, the `version` command prints the same
+version line into the output panel — handy when you want to note which
+version you're on without leaving the app.
+
 ## Examples
 
 ```sh