Filter already-added packages from template editor suggestions

Agent-Logs-Url: https://github.com/vrc-get/vrc-get/sessions/df9f3421-a51d-44c1-b81b-bab02f9f7d30

Co-authored-by: anatawa12 <22656849+anatawa12@users.noreply.github.com>

CHANGELOG-gui.md

@@ -31,6 +31,7 @@ The format is based on [Keep a Changelog].
 ### Removed
 
 ### Fixed
+- Already-added packages are now excluded from the package name suggestions in the Template Editor `#2828`
 - Fixed an issue where the progress bar flickered and did not display correct progress in environments using WebKit as the renderer. [`#2641`](https://github.com/vrc-get/vrc-get/pull/2641)
 - Fails to import UnityPackages with files in `Packages` directory `#2679`
 - null as vpmDependencies value is not allowed `#2709`

vrc-get-gui/app/_main/packages/templates/index.tsx

@@ -910,7 +910,13 @@ function TemplateEditor({
 													<Autocomplete
 														value={value.name}
 														className={"grow"}
-														options={packageCandidates}
+														options={packageCandidates.filter(
+															(c) =>
+																c.value === value.name ||
+																!packagesListContext.value.some(
+																	(p) => p.name === c.value,
+																),
+														)}
 														onChange={(value) =>
 															packagesListContext.update(id, (old) => ({
 																...old,