feat(jobs): embed.text worker (Ollama → vector(1024))

Pads nomic-embed-text's 768 dims to 1024 zeros so a later 1024-dim model
swap is a re-embed, not a migration (per master spec).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

lib/jobs/index.js

@@ -2,8 +2,9 @@ import * as queue from './queue.js';
 import * as echo from './workers/echo.js';
 import * as url from './workers/url.js';
 import * as blob from './workers/blob.js';
+import * as embed from './workers/embed.js';
 
-const WORKERS = [echo, url, blob];
+const WORKERS = [echo, url, blob, embed];
 
 export async function registerWorkers() {
   for (const w of WORKERS) {

lib/jobs/workers/embed.js

@@ -0,0 +1,29 @@
+import { embedText, padTo } from '../../ai/ollama.js';
+import { pool } from '../../db/pool.js';
+import { recordAudit } from '../../db/repos/audit.js';
+
+export const NAME = 'embed.text';
+
+const STRING_BUILDERS = {
+  page: row => `${row.title}\n\n${row.body_md || ''}`,
+  ref: row => `${row.title || ''}\n${row.summary || ''}\n${row.body_text || ''}`,
+  source_doc: row => `${row.name}\n${row.body_text || ''}`,
+  conversation: row => `${row.title || ''}\n${row.summary || ''}`
+};
+
+const TABLE = { page: 'pages', ref: 'refs', source_doc: 'source_docs', conversation: 'conversations' };
+
+export async function handler(job) {
+  const { entity_type, entity_id } = job.data;
+  const table = TABLE[entity_type];
+  if (!table) throw new Error(`unknown entity_type: ${entity_type}`);
+  const { rows: [row] } = await pool.query(`SELECT * FROM ${table} WHERE id=$1`, [entity_id]);
+  if (!row) return { skipped: 'gone' };
+  const text = STRING_BUILDERS[entity_type](row).slice(0, 6_000);
+  const v = await embedText(text);
+  const padded = padTo(v, 1024);
+  const literal = '[' + padded.join(',') + ']';
+  await pool.query(`UPDATE ${table} SET embedding=$1::vector WHERE id=$2`, [literal, entity_id]);
+  await recordAudit({ kind: 'worker', id: null }, 'update', entity_type, entity_id, null, { embedding: 'updated' });
+  return { entity_id };
+}