feat(make-pdf): out-of-tree image reads warn; --strict makes them fatal (D8.1)

Local CLI semantics stay (absolute paths and ../ still inline, like pandoc),
but never silently: an agent PDF-ing untrusted markdown can't quietly embed a
file from outside the input directory into a shareable document without a
visible warning, and --strict pipelines hard-fail. Two unit tests. Also:
TODOS.md gains the deferred e2e-harness dedup entry (D8.2).

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

TODOS.md

@@ -2397,3 +2397,21 @@ building once users hit multi-diagram docs; wedge perf is fine without it.
 
 **Effort:** S (human ~1d, CC ~30min). **Depends on:** diagram engine wedge
 shipping (lib/diagram-render bundle versioning).
+
+### P3: Dedupe the make-pdf e2e gate-test harness
+
+**What:** Five e2e files (`combined-gate`, `emoji-gate`, `diagram-gate`,
+`landscape-gate`, `format-gate`) each hand-roll the same prerequisite probe
+(binary/browse/poppler checks with CI hard-fail vs local skip), mkdtemp/rm
+lifecycle, and child-timeout constants. Extract a shared
+`make-pdf/test/e2e/helpers.ts` (prerequisites(), withWorkDir(), runGenerate()).
+
+**Why:** Review-army maintainability finding on v1.58.0.0 — the boilerplate
+diverges a little more with each new gate (diagram-gate now captures stderr
+via Bun.spawnSync while the others use execFileSync), and a future fix to the
+CI-hard-fail contract has to land five times.
+
+**Context:** Deferred at ship time (D8.2) because it's test-only churn across
+five green files at the tail of a release. Zero user-facing value; pure DRY.
+
+**Effort:** S (human ~3h, CC ~20min). **Depends on:** None.