docs: add app-local ADR log + ADR-0001 editorial illustration image style (#169)

Adds docs/adr/ scaffold (README index) and ADR-0001 documenting the v0.16.0 pivot to text-free editorial illustration with caption-as-HTML.

Agent-Session: adr-scaffold-20260617

docs/adr/README.md

@@ -0,0 +1,26 @@
+# PRAutoBlogger — App-Local ADR Log
+
+This folder is the per-repo decision log for the **PRAutoBlogger** plugin.
+It records architectural choices that affect this codebase alone.
+
+**Cross-cutting decisions** (spanning multiple plugins, shared infra, or
+CI/deploy standards) live centrally in
+`Peptide Repo CTO/docs/engineering/decisions/`.
+
+For the routing rule, required sections, and status lifecycle, read the
+canonical process document:
+`Peptide Repo CTO/docs/engineering/ADR-PROCESS.md`
+
+The canonical template for new ADRs is:
+`Peptide Repo CTO/docs/engineering/adr-template.md`
+
+## Numbering
+
+ADRs in this folder use a per-repo zero-padded sequence starting at `0001`.
+A new ADR always gets the next unused number; numbers are never reused.
+
+## Index
+
+| Number | Title | Status | Date |
+|--------|-------|--------|------|
+| [0001](0001-editorial-illustration-image-style.md) | Editorial illustration image style — pivot from comic to text-free illustration with caption-as-HTML | Accepted | 2026-05-29 |