fix: Fix product page syntax errors

1. Remove duplicate/broken code in product tables section
2. Fix PostCSS config for Tailwind 4
3. Add @tailwindcss/postcss dependency
4. Remove --production flag from Dockerfile (sharp required)

All fixes enable successful Docker build with favicon working.

node_modules/mdast-util-to-markdown/lib/handle/heading.js

@@ -0,0 +1,75 @@
+/**
+ * @import {Info, State} from 'mdast-util-to-markdown'
+ * @import {Heading, Parents} from 'mdast'
+ */
+
+import {encodeCharacterReference} from '../util/encode-character-reference.js'
+import {formatHeadingAsSetext} from '../util/format-heading-as-setext.js'
+
+/**
+ * @param {Heading} node
+ * @param {Parents | undefined} _
+ * @param {State} state
+ * @param {Info} info
+ * @returns {string}
+ */
+export function heading(node, _, state, info) {
+  const rank = Math.max(Math.min(6, node.depth || 1), 1)
+  const tracker = state.createTracker(info)
+
+  if (formatHeadingAsSetext(node, state)) {
+    const exit = state.enter('headingSetext')
+    const subexit = state.enter('phrasing')
+    const value = state.containerPhrasing(node, {
+      ...tracker.current(),
+      before: '\n',
+      after: '\n'
+    })
+    subexit()
+    exit()
+
+    return (
+      value +
+      '\n' +
+      (rank === 1 ? '=' : '-').repeat(
+        // The whole size…
+        value.length -
+          // Minus the position of the character after the last EOL (or
+          // 0 if there is none)…
+          (Math.max(value.lastIndexOf('\r'), value.lastIndexOf('\n')) + 1)
+      )
+    )
+  }
+
+  const sequence = '#'.repeat(rank)
+  const exit = state.enter('headingAtx')
+  const subexit = state.enter('phrasing')
+
+  // Note: for proper tracking, we should reset the output positions when there
+  // is no content returned, because then the space is not output.
+  // Practically, in that case, there is no content, so it doesn’t matter that
+  // we’ve tracked one too many characters.
+  tracker.move(sequence + ' ')
+
+  let value = state.containerPhrasing(node, {
+    before: '# ',
+    after: '\n',
+    ...tracker.current()
+  })
+
+  if (/^[\t ]/.test(value)) {
+    // To do: what effect has the character reference on tracking?
+    value = encodeCharacterReference(value.charCodeAt(0)) + value.slice(1)
+  }
+
+  value = value ? sequence + ' ' + value : sequence
+
+  if (state.options.closeAtx) {
+    value += ' ' + sequence
+  }
+
+  subexit()
+  exit()
+
+  return value
+}