plugins: deduplicate canonical command ID when skill name matches plugin name

[connor4312]

plugins: deduplicate canonical command ID when skill name matches plugin name

When a plugin's skill name matches the plugin name, the canonical command
ID was producing a redundant format like plugin-name:plugin-name. This
change collapses that to just plugin-name so users can invoke
/plugin-name instead of /plugin-name:plugin-name.

• Adds a check in getCanonicalPluginCommandId to return just the prefix
  when it equals the normalized command name

(Commit message generated by Copilot)

[Copilot]

Pull request overview

Adjusts plugin-provided slash command naming so that when a plugin resource’s name matches the plugin name, the canonical command ID no longer becomes redundant (plugin:plugin), enabling invocation via /plugin.

Changes:

• Add a special-case in getCanonicalPluginCommandId to return prefix when prefix === normalizedCommand.
• Keep existing behavior when the command is already explicitly prefixed (prefix:*).

Show a summary per file

File	Description
src/vs/workbench/contrib/chat/common/plugins/agentPluginService.ts	Updates canonical plugin command ID generation to avoid redundant prefix:prefix names.

Copilot's findings

Comments suppressed due to low confidence (1)

src/vs/workbench/contrib/chat/common/plugins/agentPluginService.ts:76

• This changes the canonical slash command ID for root plugin resources from prefix:prefix to just prefix, which breaks any existing invocations/configuration that still use the old prefix:prefix form (there’s no normalization/aliasing in resolvePromptSlashCommand; it does an exact name match). Consider keeping prefix:prefix as a supported alias (or normalizing user input) so both forms continue to resolve, and so users can still disambiguate if another prompt/skill named prefix exists.

	if (prefix === normalizedCommand) {
		return prefix;
	}

	return `${prefix}:${normalizedCommand}`;

• Files reviewed: 1/1 changed files
• Comments generated: 2