fix(lessons): a lesson's name is one claim on one line (#4797)

#4797 "A lesson's what takes a whole narrative, and the narrative becomes
its name". `what` is the title every listing and menu prints. Nothing
enforced its documented "one line", so lessons written with the incident
in `what` printed up to ~1,500 characters as a menu line, buried the
claim, and diluted the trigger in the embedded title. That was 14 of the
39 lessons on this install.

- lessons.require_claim refuses a `what` over WHAT_MAX_CHARS (240) or
  running over several lines. The refusal says the story goes in
  `insight`.
- Both doors call it before writing:
  - MCP create_lesson / update_lesson;
  - REST create / update.
  An update checks only a NEW name, so a lesson stored with a long one can
  still take the edit that repairs it.
- lessons.claim_line is the display half. _menu_name shows an over-long
  stored name as its first sentence marked " …", because a door guard
  does not undo rows already stored and an unrepaired install would keep
  printing them.
- The tool docstrings state the bound.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/scribe/services/plugin_context.py

@@ -35,7 +35,7 @@ from scribe.services.embeddings import (
     semantic_search_rules,
 )
 from scribe.services import lesson_rules as lesson_rules_svc
-from scribe.services.lessons import LESSON_NOTE_TYPE
+from scribe.services.lessons import LESSON_NOTE_TYPE, claim_line
 from scribe.services.note_usage import record_surfaced
 from scribe.services.rule_usage import record_rule_surfaced
 from scribe.services.supersession import superseded_ids
@@ -89,7 +89,8 @@ def _menu_name(title: str | None, note_type: str | None, data=None, body: str |
         from scribe.services.embeddings import untrigger_title
         from scribe.services.lessons import lesson_trigger
         trigger = lesson_trigger(SimpleNamespace(data=data, body=body or ""))
-        return untrigger_title(title, trigger).strip() or title
+        # One line even when the stored name is a story (#4797).
+        return claim_line(untrigger_title(title, trigger).strip() or title)
     return title