Preserve plugin and hook semantics while finishing the hook-pipeline merge

The merge now keeps plugin lifecycle management, plugin tool permissions,
hook abort/progress handling, permission-rule config, and shared slash-command
help aligned across runtime and CLI codepaths.

Constraint: Merge had to retain both plugin runtime behavior and hook-pipeline permission/abort features
Rejected: Drop plugin-aware runtime paths during merge | would regress installed plugin hooks and lifecycle handling
Rejected: Prefer hook-pipeline tool permissions over the global tool registry | would lose plugin tool permission mapping
Confidence: high
Scope-risk: moderate
Reversibility: clean
Directive: Keep runtime hook flow, permission policy wiring, and slash-command surfaces synchronized across crates during future merges
Tested: cargo test; cargo fmt --all --check; git diff --check
Not-tested: Live networked ANTHROPIC_API_KEY smoke path

rust/crates/commands/src/lib.rs

@@ -201,8 +201,8 @@ const SLASH_COMMAND_SPECS: &[SlashCommandSpec] = &[
         resume_supported: false,
     },
     SlashCommandSpec {
-        name: "plugin",
-        aliases: &["plugins", "marketplace"],
+        name: "plugins",
+        aliases: &["plugin", "marketplace"],
         summary: "Manage Claude Code plugins",
         argument_hint: Some(
             "[list|install <path>|enable <name>|disable <name>|uninstall <id>|update <id>]",
@@ -1229,7 +1229,7 @@ mod tests {
         assert!(help.contains(
             "/plugins [list|install <path>|enable <name>|disable <name>|uninstall <id>|update <id>]"
         ));
-        assert_eq!(slash_command_specs().len(), 23);
+        assert_eq!(slash_command_specs().len(), 25);
         assert_eq!(resume_supported_slash_commands().len(), 11);
     }