feat: resolve NIP-19 identifiers in article content

- Add nostrUriResolver utility to detect and replace nostr: URIs
- Support npub, note, nprofile, nevent, and naddr identifiers
- Convert nostr: URIs to clickable njump.me links
- Process markdown before rendering to handle nostr mentions
- Add CSS styling for nostr-uri-link class
- Implements NIP-19 and NIP-27 (nostr: URI scheme)

Nostr-native articles can now contain references like:
- nostr:npub1... → @npub1abc...
- nostr:note1... → note:note1abc...
- nostr:naddr1... → article:identifier

All identifiers become clickable links to njump.me

src/utils/nostrUriResolver.tsx

@@ -0,0 +1,134 @@
+import React from 'react'
+import { decode, npubEncode, noteEncode } from 'nostr-tools/nip19'
+import { DecodeResult } from 'nostr-tools/nip19'
+
+/**
+ * Regular expression to match nostr: URIs and bare NIP-19 identifiers
+ * Matches: nostr:npub1..., nostr:note1..., nostr:nprofile1..., nostr:nevent1..., nostr:naddr1...
+ * Also matches bare identifiers without the nostr: prefix
+ */
+const NOSTR_URI_REGEX = /(?:nostr:)?((npub|note|nprofile|nevent|naddr)1[qpzry9x8gf2tvdw0s3jn54khce6mua7l]{58,})/gi
+
+/**
+ * Extract all nostr URIs from text
+ */
+export function extractNostrUris(text: string): string[] {
+  const matches = text.match(NOSTR_URI_REGEX)
+  if (!matches) return []
+  
+  // Extract just the NIP-19 identifier (without nostr: prefix)
+  return matches.map(match => {
+    const cleanMatch = match.replace(/^nostr:/, '')
+    return cleanMatch
+  })
+}
+
+/**
+ * Decode a NIP-19 identifier and return a human-readable link
+ */
+export function createNostrLink(encoded: string): string {
+  try {
+    const decoded = decode(encoded)
+    
+    switch (decoded.type) {
+      case 'npub':
+        return `https://njump.me/${encoded}`
+      case 'nprofile':
+        return `https://njump.me/${encoded}`
+      case 'note':
+        return `https://njump.me/${encoded}`
+      case 'nevent':
+        return `https://njump.me/${encoded}`
+      case 'naddr':
+        return `https://njump.me/${encoded}`
+      default:
+        return `https://njump.me/${encoded}`
+    }
+  } catch (error) {
+    console.warn('Failed to decode nostr URI:', encoded, error)
+    return `https://njump.me/${encoded}`
+  }
+}
+
+/**
+ * Get a display label for a nostr URI
+ */
+export function getNostrUriLabel(encoded: string): string {
+  try {
+    const decoded = decode(encoded)
+    
+    switch (decoded.type) {
+      case 'npub':
+        return `@${encoded.slice(0, 12)}...`
+      case 'nprofile':
+        const npub = npubEncode(decoded.data.pubkey)
+        return `@${npub.slice(0, 12)}...`
+      case 'note':
+        return `note:${encoded.slice(5, 12)}...`
+      case 'nevent':
+        const note = noteEncode(decoded.data.id)
+        return `note:${note.slice(5, 12)}...`
+      case 'naddr':
+        return `article:${decoded.data.identifier || 'untitled'}`
+      default:
+        return encoded.slice(0, 16) + '...'
+    }
+  } catch (error) {
+    return encoded.slice(0, 16) + '...'
+  }
+}
+
+/**
+ * Replace nostr: URIs in markdown with proper markdown links
+ * This converts: nostr:npub1... to [label](link)
+ */
+export function replaceNostrUrisInMarkdown(markdown: string): string {
+  return markdown.replace(NOSTR_URI_REGEX, (match) => {
+    // Extract just the NIP-19 identifier (without nostr: prefix)
+    const encoded = match.replace(/^nostr:/, '')
+    const link = createNostrLink(encoded)
+    const label = getNostrUriLabel(encoded)
+    
+    return `[${label}](${link})`
+  })
+}
+
+/**
+ * Replace nostr: URIs in HTML with clickable links
+ * This is used when processing HTML content directly
+ */
+export function replaceNostrUrisInHTML(html: string): string {
+  return html.replace(NOSTR_URI_REGEX, (match) => {
+    // Extract just the NIP-19 identifier (without nostr: prefix)
+    const encoded = match.replace(/^nostr:/, '')
+    const link = createNostrLink(encoded)
+    const label = getNostrUriLabel(encoded)
+    
+    return `<a href="${link}" class="nostr-uri-link" target="_blank" rel="noopener noreferrer">${label}</a>`
+  })
+}
+
+/**
+ * Get decoded information from a nostr URI for detailed display
+ */
+export function getNostrUriInfo(encoded: string): {
+  type: string
+  decoded: DecodeResult | null
+  link: string
+  label: string
+} {
+  let decoded: DecodeResult | null = null
+  try {
+    decoded = decode(encoded)
+  } catch (error) {
+    // ignore decoding errors
+  }
+  
+  return {
+    type: decoded?.type || 'unknown',
+    decoded,
+    link: createNostrLink(encoded),
+    label: getNostrUriLabel(encoded)
+  }
+}
+