feat(mcp): S5 — issue-kind guidance across all instruction surfaces

Plan #825 (T2 — Issues task_kind) shipped S1–S4 but its S5 docs slice
never landed, so every behavioral surface the plugin pushes to the agent
still described the pre-kind convention ("tag `issue`" on a create_note).
Result: agents fixed bugs without reaching for kind=issue and dumped the
work as logs on unrelated open tasks.

- _INSTRUCTIONS: rewrite the "record a problem" bullet to
  create_task(kind="issue") with symptom→cause→fix + arose_from_id /
  system_ids, and an explicit "not a work-log on an unrelated task"; add
  Issue + System to the hierarchy section.
- skills/systematic-debugging, verification: drop "tag `issue`" /
  create_note-issue, point at create_task(kind="issue").
- skills/using-scribe: add issues/systems to the entity list + reflex #6.
- hooks/scribe_static_context: fix → its own issue on the keyless floor.

Instance-agnostic, prose-only; no schema or tool-behavior change.
Pairs with always-on rule #118. Issue: #855.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plugin/skills/using-scribe/SKILL.md

@@ -5,10 +5,11 @@ description: Use at the START of every session, and before answering anything ab
 
 # Using Scribe
 
-Scribe is the operator's self-hosted second brain (notes, tasks, projects,
-milestones, events, typed entities) and rulebook, reachable through the bundled
-`scribe` MCP server. Its value is mostly in what it **already holds** — so make
-reading it a reflex, not something you wait to be asked for.
+Scribe is the operator's self-hosted second brain (notes, tasks, issues,
+projects, milestones, systems, events, typed entities) and rulebook, reachable
+through the bundled `scribe` MCP server. Its value is mostly in what it
+**already holds** — so make reading it a reflex, not something you wait to be
+asked for.
 
 ## Do this first (every session)
 
@@ -72,6 +73,12 @@ Two constraints on *how* that's achieved:
 5. **Keep state honest.** Set a task `in_progress` when you start it, `done` the
    moment it's complete; log progress as you go.
 
+6. **Fixes are issues, not work-logs.** When you fix a problem — even one solved
+   in passing — record it as its own issue (`create_task(kind="issue")`) with
+   symptom → root cause → fix, optionally linked to the task it arose from
+   (`arose_from_id`) and the subsystem it touches (`system_ids`). Don't bury a
+   fix as a work-log line on whatever task happened to be open.
+
 ## Stay inside the active project's scope
 
 Once a project is in scope — you called `enter_project`, or the working repo is