fuentes automaticas: el CODIGO agrega la fuente, no el LLM (ronda 13-14)

- sources.mjs (nuevo): selectSource() + attribute() — seleccion de material
  ≤72h con score≥6, atribucion en formato fijo.
- core.mjs: las 4 piezas (digest/opinion/reflection/events) generan sobre
  la fuente seleccionada y el codigo agrega la atribucion DESPUES del LLM.
- guard.mjs:
  * R1/R2/R4/R5/R8 evaluan el TEXTO SIN la linea de atribucion
  * R3/R7 ven el texto completo (con atribucion) — la fuente garantiza
    que pasen
  * R9 (nueva): la pieza debe compartir terminos del dominito con su fuente
  * R8: superlativos estrechos (sin never/only que dejaban pasar aforismos)
  * deletion anadido a METADATA_TYPES (no cuenta hacia el tope diario)
- guard.test.mjs: 24/24 verdes (incluye tests R14a/c/d)

runtime/sources.mjs

@@ -0,0 +1,45 @@
+// sources.mjs — selección de material de origen y atribución automática
+// Ronda 13: el CÓDIGO agrega la fuente, no el LLM.
+import { readFileSync } from 'node:fs'
+import { createRequire } from 'node:module'
+const require_ = createRequire(import.meta.url)
+
+let _pool = null
+function pool() {
+  if (!_pool) {
+    const pg = require_('/srv/cayce-core/node_modules/pg')
+    const env = Object.fromEntries(
+      readFileSync('/srv/hardcap-news/backend/.env', 'utf8').split('\n').filter(l => l.includes('=')).map(l => [l.slice(0, l.indexOf('=')), l.slice(l.indexOf('=') + 1)])
+    )
+    _pool = new pg.Pool({ connectionString: env.DATABASE_URL })
+  }
+  return _pool
+}
+
+export async function selectSource(topic = null) {
+  const p = pool()
+  const q = topic
+    ? `SELECT id, title, "originalUrl", "publishedAt"::text FROM articles WHERE status='PUBLISHED' AND "relevanceScore">=6 AND "publishedAt">now()-interval '72 hours' AND $1=ANY(topics) ORDER BY "relevanceScore" DESC LIMIT 1`
+    : `SELECT id, title, "originalUrl", "publishedAt"::text FROM articles WHERE status='PUBLISHED' AND "relevanceScore">=6 AND "publishedAt">now()-interval '72 hours' ORDER BY "relevanceScore" DESC LIMIT 1`
+  const { rows } = await p.query(q, topic ? [topic] : [])
+  return rows[0] || null
+}
+
+export async function selectBatch(n = 5, topic = null) {
+  const p = pool()
+  const q = topic
+    ? `SELECT id, title, summary, "originalUrl", "publishedAt"::text, "relevanceScore" FROM articles WHERE status='PUBLISHED' AND "relevanceScore">=6 AND "publishedAt">now()-interval '72 hours' AND $1=ANY(topics) ORDER BY "relevanceScore" DESC LIMIT $2`
+    : `SELECT id, title, summary, "originalUrl", "publishedAt"::text, "relevanceScore" FROM articles WHERE status='PUBLISHED' AND "relevanceScore">=6 AND "publishedAt">now()-interval '72 hours' ORDER BY "relevanceScore" DESC LIMIT $1`
+  const { rows } = await p.query(q, topic ? [topic, n] : [n])
+  return rows
+}
+
+export function attribute(source) {
+  if (!source) return ''
+  const date = (source.publishedAt || '').slice(0, 10) || new Date().toISOString().slice(0, 10)
+  return `\n\n— fuente: ${source.originalUrl} · ${date}`
+}
+
+export function attributeURL(url, dateStr) {
+  return `\n\n— fuente: ${url} · ${dateStr}`
+}