Add ADR for code block syntax highlighting and ADR template

Author: bigtiger

docs/adr/0001-code-block-syntax-highlighting.md

@@ -0,0 +1,32 @@
+# ADR 0001: Code Block Syntax Highlighting
+
+**Date:** 2026-03-29
+**Status:** Done
+
+## Context
+
+The theme needed support for displaying code blocks in posts and pages. Ghost's Koenig editor outputs `<pre><code class="language-*">` markup but the theme had no styles or syntax highlighting for it.
+
+## Decisions
+
+### Prism.js via CDN
+
+Prism.js is loaded from jsDelivr with the autoloader plugin rather than bundled into `app.js`. This keeps the theme build lean and means any language is supported on demand without maintaining a list of grammar files.
+
+### Token colors from the design system
+
+Syntax token colors are mapped to existing CSS variables (`--color-blue`, `--color-green`, `--color-red`, `--color-yellow`) rather than introducing a third-party theme. This keeps the code blocks feeling native to the site.
+
+### Language label via JS + CSS
+
+Ghost's Markdown card puts `language-*` on the `<code>` element, not the `<pre>`. A script in `post.js` reads the class, extracts the language name, and sets it as `data-language` on the `<pre>`. A CSS `::before` pseudo-element renders the label. This avoids a dependency on Ghost-specific markup that could change.
+
+### Line wrap toggle via `<!--wrap-->` HTML card
+
+Ghost provides no mechanism to add classes to code block elements from the editor. Authors who want line wrapping instead of horizontal scroll can insert an HTML card containing `<!--wrap-->` immediately before a code block. A script in `post.js` detects the comment node and adds a `.wrap` class to the `<pre>`.
+
+## Alternatives Considered
+
+- **Bundling Prism grammars** — would avoid the CDN dependency but add build complexity and require updating the bundle when new languages are needed.
+- **A Prism theme (e.g. Tomorrow Night)** — rejected in favor of token colors derived from the design system.
+- **Default line wrapping** — rejected because wrapping breaks visual indentation and makes code harder to scan. Opt-in per block is more appropriate.

docs/adr/template.md

@@ -0,0 +1,24 @@
+# ADR XXXX: Title
+
+**Date:** YYYY-MM-DD
+**Status:** Proposed
+
+<!-- Status options:
+  Proposed   — under discussion, not yet adopted
+  Accepted   — deliberate choice made after weighing options
+  Done       — written after the fact; documents what was built and why
+  Deprecated — no longer relevant
+  Superseded by ADR-XXXX — replaced by a later decision
+-->
+
+## Context
+
+What problem were you solving? What constraints or forces shaped the decision?
+
+## Decisions
+
+What was decided, and why?
+
+## Alternatives Considered
+
+What else was on the table and why was it ruled out?