add pictures

add_pages_pictures.sql

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+-- add_pages_pictures.sql
+--
+-- Adds the image URLs found on crawled pages to `pages.pictures`.
+--
+-- Purpose:
+--   The crawler stores every absolute image URL of a page (img src,
+--   srcset, <picture>/<source>, og:image, twitter:image, link
+--   rel="image_src") in `pages.pictures`, so the search UI can offer an
+--   image tab without downloading or storing the images themselves.
+--
+-- Run once on the jonassearch database as its owner, e.g.:
+--   psql -h 127.0.0.1 -p 25432 -U jonassearch -d jonassearch \
+--       -f add_pages_pictures.sql
+--
+-- Safe to run repeatedly (IF NOT EXISTS) and safe while the crawler is
+-- running: the column is added as a nullable text[] and existing rows
+-- are not rewritten. The crawler always writes an array (possibly
+-- empty) from version 5 on; queries treat NULL and '{}' the same.
+--
+-- If the column already exists (e.g. created by an earlier schema), the
+-- statement is a no-op and the stored data is left untouched.
+
+ALTER TABLE pages ADD COLUMN IF NOT EXISTS pictures text[];
+
+-- New rows without an explicit value get an empty array. This only
+-- changes table metadata; it does not rewrite existing rows.
+ALTER TABLE pages ALTER COLUMN pictures SET DEFAULT '{}';