plan-ceo-review: remove the handoff-note reader and cleanup for files nothing writes (s04 F6, s04 F7)

CEO handoff notes (*-ceo-handoff-*.md) have not been written since v0.11.5.1;
no template, resolver or bin script produces them. The reader cost a bash
call on every CEO run, depended on $SLUG/$BRANCH from another shell, and
looked under $GSTACK_STATE_ROOT where pre-state-root notes never lived.

W7a pin: test/skill-ceo-section-ordering.test.ts:320 sliced up to the
removed '## Handoff Note Cleanup' heading; it now slices to the next heading
('## Review Log') with the same assertions.
Note: the ceo-mode-option / ceo-mode-prerequisite PTY cases fail under the
image's Bun 1.3.14 with or without this change and pass under Bun 1.4.0.
expected red until the regeneration commit

test/skill-ceo-section-ordering.test.ts

@@ -317,7 +317,7 @@ test('CEO output stages prepare body before report and publish only after verifi
   expect(section).toContain('no stage depends on a completion log written later');
   expect(section).toContain('After the report Read-back gate passes');
   expect(section).toContain('Do not append it after the report in the file');
-  const chat = section.slice(section.indexOf('If no plan/report write is permitted'), section.indexOf('## Handoff Note Cleanup'));
+  const chat = section.slice(section.indexOf('If no plan/report write is permitted'), section.indexOf('## Review Log'));
   expect(chat).toContain('complete plan, report and summary as not persisted, then use **Gate outcome: Blocked**');
   expect(chat).toContain('without claiming saved completion');
   expect(chat).toContain('skip Review Log, success telemetry and the next-skill handoff');