feat: implement wiki-linked categories with graph and backlinks integration

Add complete category system that integrates with Obsidian's wiki-linked
category frontmatter. Categories appear as pills on pages and link directly
to category notes (not aggregation pages).

Features:
- Parse [[Page Name]] syntax from category frontmatter
- Display category pills styled like tags
- Link directly to category notes
- Integrate with graph view connections
- Enable bidirectional backlinks
- Preserve case in category slugs

Implementation:
- Added extractWikiLinks() to frontmatter transformer
- Created CategoryList component for pill rendering
- Modified links transformer to include categories in links array
- Updated contentIndex to export category metadata
- Added i18n strings for category UI elements
- Set includeEmptyFiles: true to show empty category pages in graph

Files modified:
- quartz/plugins/transformers/frontmatter.ts
- quartz/plugins/transformers/links.ts
- quartz/plugins/emitters/contentIndex.tsx
- quartz/components/CategoryList.tsx (new)
- quartz/components/pages/CategoryContent.tsx (new)
- quartz/plugins/emitters/categoryPage.tsx (new)
- quartz/i18n/locales/en-US.ts
- quartz/i18n/locales/definition.ts
- quartz/components/index.ts
- quartz.layout.ts
- quartz.config.ts
- README.md (updated with Quartz updater documentation)

Security: Comprehensive privacy review confirms NO information leaks from
private folder. All ignore patterns working correctly.

Docs: Added CUSTOMIZATIONS.md with complete feature documentation,
implementation details, and privacy audit results.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

quartz/plugins/transformers/frontmatter.ts

@@ -3,7 +3,7 @@ import remarkFrontmatter from "remark-frontmatter"
 import { QuartzTransformerPlugin } from "../types"
 import yaml from "js-yaml"
 import toml from "toml"
-import { FilePath, FullSlug, getFileExtension, slugifyFilePath, slugTag } from "../../util/path"
+import { FilePath, FullSlug, getFileExtension, simplifySlug, slugifyFilePath, slugTag } from "../../util/path"
 import { QuartzPluginData } from "../vfile"
 import { i18n } from "../../i18n"
 
@@ -40,6 +40,14 @@ function coerceToArray(input: string | string[]): string[] | undefined {
     .map((tag: string | number) => tag.toString())
 }
 
+function extractWikiLinks(input: string[]): string[] {
+  // Extract page names from wiki links like [[Page Name]] -> Page Name
+  return input.map((item) => {
+    const wikiLinkMatch = item.match(/^\[\[(.+?)\]\]$/)
+    return wikiLinkMatch ? wikiLinkMatch[1] : item
+  })
+}
+
 function getAliasSlugs(aliases: string[]): FullSlug[] {
   const res: FullSlug[] = []
   for (const alias of aliases) {
@@ -80,6 +88,17 @@ export const FrontMatter: QuartzTransformerPlugin<Partial<Options>> = (userOpts)
             const tags = coerceToArray(coalesceAliases(data, ["tags", "tag"]))
             if (tags) data.tags = [...new Set(tags.map((tag: string) => slugTag(tag)))]
 
+            const categories = coerceToArray(coalesceAliases(data, ["categories", "category"]))
+            if (categories) {
+              // Extract page names from wiki links and slugify them like regular page links
+              const categoryNames = extractWikiLinks(categories)
+              data.categories = [...new Set(categoryNames.map((cat: string) => {
+                // Use slugifyFilePath to match how pages are slugified
+                const slug = slugifyFilePath((cat + ".md") as any)
+                return simplifySlug(slug)
+              }))]
+            }
+
             const aliases = coerceToArray(coalesceAliases(data, ["aliases", "alias"]))
             if (aliases) {
               data.aliases = aliases // frontmatter
@@ -139,6 +158,7 @@ declare module "vfile" {
       title: string
     } & Partial<{
         tags: string[]
+        categories: string[]
         aliases: string[]
         modified: string
         created: string

quartz/plugins/transformers/links.ts

@@ -159,7 +159,9 @@ export const CrawlLinks: QuartzTransformerPlugin<Partial<Options>> = (userOpts)
               }
             })
 
-            file.data.links = [...outgoing]
+            // Include categories as links for backlinks and graph
+            const categories = file.data.frontmatter?.categories ?? []
+            file.data.links = [...outgoing, ...categories]
           }
         },
       ]