docs(adr): add adr-template.md scaffold (ADR-023)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/decisions/adr-template.md

@@ -0,0 +1,38 @@
+# ADR-NNN — <Title>: <optional clarifying subtitle>
+
+<!-- Filename: NNN-kebab-title.md (zero-padded, monotonic, never reused).
+     Register a row in CLAUDE.md "Further reading" when this ADR is created.
+     Sections below in order. Mandatory: Status, Context, Decision, Consequences.
+     Delete this comment and any optional section you don't use. -->
+
+## Status
+
+Accepted (YYYY-MM-DD)
+<!-- Lifecycle: "Accepted (YYYY-MM-DD)" → later "Superseded by ADR-NNN (YYYY-MM-DD)"
+     or "Deprecated (YYYY-MM-DD)" + one-line why. Optional trailing note OK, e.g.
+     "Accepted (2026-06-10). Doctrine ADR — pins policy, builds nothing yet." -->
+
+## Context
+
+<!-- The forces, the problem, what exists today, why now. -->
+
+## Decision
+
+<!-- What we are doing. Use numbered sub-decisions (### 1. ...) for multi-part ADRs. -->
+
+## Consequences
+
+<!-- Results, trade-offs explicitly accepted, follow-on work. -->
+
+<!-- Optional sections — uncomment any that genuinely apply; never pad:
+
+## Scope — explicit in / out-of-scope boundaries.
+
+## Guardrails — how the decision is mechanically enforced (lint, CI, hooks).
+
+## What was ruled out — rejected alternatives, each with its reason.
+
+## Verified facts (ADR-014) — verified: <subject> · <tool> <version> · <source> · <YYYY-MM-DD>
+
+## Related — links to other ADRs by number; bidirectional for Supersedes/Superseded-by.
+-->