Add OpenAI plugin submission bundle

Build a Codex-native OpenAI plugin with bundled hooks, public listing metadata, submission guidance, privacy coverage, and regression tests.

AI assistance: OpenAI Codex prepared and validated these changes under maintainer direction.

.github/skills/impeccable/scripts/context-signals.mjs

@@ -1,6 +1,6 @@
 #!/usr/bin/env node
 /**
- * Context-signals gatherer for the bare `{{command_prefix}}impeccable`
+ * Context-signals gatherer for the bare `/impeccable`
  * (no-argument) path. Collects cheap, deterministic signals about the current
  * project and emits them as JSON.
  *

.github/skills/impeccable/scripts/pin.mjs

@@ -100,9 +100,9 @@ user-invocable: true
 
 ${PIN_MARKER}
 
-This is a pinned shortcut for \`{{command_prefix}}impeccable ${command}\`.
+This is a pinned shortcut for \`/impeccable ${command}\`.
 
-Invoke {{command_prefix}}impeccable ${command}, passing along any arguments provided here, and follow its instructions.
+Invoke /impeccable ${command}, passing along any arguments provided here, and follow its instructions.
 `;
 }