test: configure comprehensive markdown linting with Docsy best practices

Configure markdownlint with rules aligned to technical documentation
standards and Docsy theme conventions.

Design Decisions:
- Enable core quality rules (heading hierarchy, consistent list styles)
- Allow inline HTML for Docsy shortcodes and components
- Permit bare URLs (common in technical documentation)
- Make code block language hints optional (pragmatic for existing content)
- Set maximum 2 consecutive blank lines (balanced readability)
- Enforce single trailing newline (POSIX standard)
- Use asterisk for unordered lists (consistency)
- Allow 2-space list indentation (Markdown standard)

Auto-fixed Issues:
- Converted dash lists to asterisk lists (568 fixes)
- Removed trailing spaces (211 fixes)
- Added missing trailing newlines (74 fixes)
- Added blank lines around lists and headings (100+ fixes)

Remaining Style Warnings (intentionally accepted):
- MD029: List numbering variations in meeting notes (75 instances)
- MD036: Bold text for section headers in ADRs (13 instances)
- MD025: Multiple H1 in notes/brainstorming docs (10 instances)
- MD032/MD022: Minor spacing variations (15 instances)

Test Results:
✅ Hugo build: 227 pages generated successfully
✅ HTML validation: No errors
✅ Link checking: All links valid (except dev-only livereload)
✅ Markdown linting: Only non-critical style warnings remain

The configuration balances strict quality checks with pragmatic
flexibility for diverse content types (documentation, ADRs, meeting
notes, tutorials).

.markdownlint.json

@@ -1,8 +1,25 @@
 {
+  "$schema": "https://raw.githubusercontent.com/DavidAnson/markdownlint/main/schema/markdownlint-config-schema.json",
   "default": true,
+  "MD001": true,
+  "MD003": { "style": "atx" },
+  "MD004": { "style": "asterisk" },
+  "MD007": { "indent": 2 },
+  "MD009": { "br_spaces": 2 },
+  "MD010": { "code_blocks": false },
+  "MD012": { "maximum": 2 },
   "MD013": false,
-  "MD033": false,
-  "MD041": false,
+  "MD022": { "lines_above": 1, "lines_below": 1 },
   "MD024": { "siblings_only": true },
-  "MD025": { "front_matter_title": "" }
+  "MD025": { "front_matter_title": "" },
+  "MD026": { "punctuation": ".,;:" },
+  "MD029": { "style": "ordered" },
+  "MD031": { "list_items": false },
+  "MD032": true,
+  "MD033": { "allowed_elements": ["div", "span", "a", "img", "br", "details", "summary"] },
+  "MD034": false,
+  "MD040": false,
+  "MD041": false,
+  "MD045": false,
+  "MD047": true
 }