fix(desktop): brand the install and updater cache directories

CHANGELOG.md

@@ -13,6 +13,19 @@ file is the human-readable summary of what changed and why.
   carried a redundant copy of themselves: a second, nested copy of the same
   tarball, packed in by accident whenever a release was retried. Removing it
   takes each platform package from ~112MB back to ~55MB.
+- **The desktop app installs to a folder named after CoDev** — on Windows it
+  installed itself into `%LOCALAPPDATA%\Programs\@opencode-aidesktop`, and kept
+  its downloaded updates in `@opencode-aidesktop-updater` beside it. Both names
+  came from an internal package id that was never meant to be read, by way of a
+  packaging rule that uses it rather than the product name for a per-user
+  install. They are now `codev` and `codev-updater` (`codev-beta`/`codev-dev` on
+  those channels, which previously shared one folder with each other and with
+  the release build). Already-installed copies stay where they are and keep
+  updating — the installer reuses the location it recorded — so this changes
+  where a fresh install lands, not where an existing one lives; a machine that
+  had downloaded an update leaves the old cache folder behind, which is safe to
+  delete. Linux and macOS are unaffected: the `.deb` package name is already
+  `codev`, and nothing on macOS is derived from this name.
 
 ### Updates