feat(boss): file skill-system deficiencies to the plugin's own tracker

Under /boss only, when the orchestrator hits a durable deficiency in the
plugin itself (a skill, agent, convention, or pipeline/cascade gap)
mid-run, it files an issue against the plugin's own tracker and continues,
marking provenance with a body block — no new label, so the fixed work-type
vocabulary stays intact.

Adds the trigger and its evidence gate (a citable path:line inside the
plugin), dedupe-as-gate over open and recently-closed issues, and the
discipline that filing is neither a notify event nor a substitute for a due
bounce-back. Wires the new section into issue/SKILL.md (boss joins the
issue-filing callers) and docs/conventions.md (Issue-tracker pointer).

closes #9

docs/conventions.md

@@ -124,6 +124,13 @@ records its fork decisions on the run's reference issue there, and an
 ad-hoc `spec-skeptic` `scope-fork` dispatch reads single issues with
 their comment threads from there.
 
+Separately, `/boss` files **skill-system deficiencies** — faults in the
+plugin itself, hit mid-run — against the **plugin's own** tracker (slug
+derived from the plugin checkout's git remote), provenance carried by a
+body block and never a new label. The skills meta-repo is not driven
+through its own pipeline, so this tracker and a project's tracker never
+coincide. See `../boss/SKILL.md` § Skill-system feedback.
+
 ## Pipeline
 
 The phase set, the gates, and the conditional dispatch are **fixed**