refactor(systems): one seam — the Systems question rides every read and write of a record

Scribe issue #2570, from the operator's challenge: the invariant is
"always be asking whether what you're touching is a System's territory
and whether the work is filed there" — not a nudge in one corner. The
prior shape failed it twice: the hint fired only on creates (with a
special-cased zero-Systems branch), and get_task/get_note returned
records WITHOUT their Systems, so the read-side reflex had nothing to
fire on (same per-kind asymmetry as #2481).

- attach_systems(): single helper used by get/create/update for tasks,
  notes, and snippets, plus add_task_log. Tagged records always show
  `systems`; an untagged project record carries the `systems_hint`
  question instead. Neither field attaches empty (#2483). Hint is
  owner-only; everything fail-open (#2109).
- untagged_systems_hint unified to ONE question — the vocabulary
  listing varies, the question doesn't; the zero-Systems branch stops
  being special text.
- Docstrings state the uniform contract; floor prose now names the
  read-side reflex (systems visible -> list_system_records the pile).
- Plugin 0.1.27 -> 0.1.28.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

plugin/hooks/scribe_static_context.md

@@ -46,9 +46,12 @@ for the operator's work, and as your own working memory across sessions.
   missing Systems: a pass that walks the subsystems has just enumerated the
   vocabulary, so mint what it names. Create liberally; the duplicate gate on
   `create_system` (and reviewing the existing list) is the guardrail against
-  sprawl, not restraint. Untagged writes come back with a `systems_hint` —
-  treat it as the tagging question asked at exactly the right moment, not as
-  noise to skip past.
+  sprawl, not restraint. Every read and write of a project record shows its
+  `systems` — that is the "am I in a System's territory?" signal, and
+  `list_system_records` reads that territory's whole pile before you work in
+  it. An untagged project record carries the `systems_hint` question instead,
+  on creates, updates, and work-logs alike — treat it as the tagging question
+  asked at the moment of work, not as noise to skip past.
 - **Reuse before rebuilding** — before writing a new helper/utility/component,
   search recorded **snippets** (reusable code recorded once for recall) and
   reuse the prior art instead of re-solving it; when you build something