Add markdown linting infrastructure

.markdownlint.yaml

@@ -0,0 +1,56 @@
+# markdownlint configuration
+# See https://github.com/DavidAnson/markdownlint/blob/main/doc/Rules.md
+
+# Heading hierarchy rules
+MD001: true  # heading-increment - headings should only increment by one level at a time
+MD025: true  # single-title/single-h1 - documents should have a single top-level heading
+
+# Heading style rules
+MD003:       # heading-style - heading style should be consistent
+  style: atx # Use ATX style (##) not Setext style (underlines)
+MD018: true  # no-missing-space-atx - no space after hash on atx style heading
+MD019: true  # no-multiple-space-atx - multiple spaces after hash on atx style heading
+MD023: true  # heading-start-left - headings must start at the beginning of the line
+MD024:       # no-duplicate-heading - multiple headings with the same content
+  siblings_only: true # Allow duplicate headings in different sections
+MD026:       # no-trailing-punctuation - trailing punctuation in heading
+  punctuation: ".,;:!" # Don't allow these, but allow ? for questions
+
+# First line rules
+MD041: false # first-line-heading/first-line-h1 - disabled because we use frontmatter
+
+# Line length
+MD013: false # line-length - disabled for prose content
+
+# Code blocks
+MD046:       # code-block-style - code block style should be consistent
+  style: fenced # Use fenced code blocks (```) not indented
+
+# Lists
+MD004:       # ul-style - unordered list style should be consistent
+  style: dash # Use dashes for unordered lists
+MD029:       # ol-prefix - ordered list item prefix
+  style: ordered # Use sequential numbers (1, 2, 3) not all 1s
+MD030:       # list-marker-space - spaces after list markers
+  ul_single: 1
+  ul_multi: 1
+  ol_single: 1
+  ol_multi: 1
+
+# Blank lines
+MD012:       # no-multiple-blanks - multiple consecutive blank lines
+  maximum: 2 # Allow up to 2 blank lines for visual separation
+MD022:       # blanks-around-headings - headings should be surrounded by blank lines
+  lines_above: 1
+  lines_below: 1
+
+# Inline HTML
+MD033: false # no-inline-html - disabled to allow inline HTML in MDX
+
+# Emphasis
+MD036: false # no-emphasis-as-heading - disabled to allow emphasized text that looks like headings
+
+# Whitespace and formatting
+MD009: false # no-trailing-spaces - disabled as trailing spaces don't affect rendering
+MD007: false # ul-indent - disabled to allow flexible list indentation
+MD060: false # table-column-style - disabled as table alignment is cosmetic

justfile

@@ -99,6 +99,10 @@ lint:
 lint-fix:
     npm run lint:fix
 
+# Lint-markdown: runs markdownlint on content files
+lint-markdown:
+    npm run lint:markdown
+
 # Validate: runs all validation checks (lint + spellcheck + build + links)
 validate:
     npm run validate:all