refactor: ValueCleaner is the named choke point (H1)

The choke point moves out of AttrWriter into ValueCleaner (catalog, the
composition's VariableRef, sanitizer): clean() (was AttrWriter::cleanValue),
kindOf(), guardPath() and the private cleanNode/kind/unknownKind/tightens with
VALUE_KEY, URL_KEY, URL_SEGMENT, STRICTNESS, BUILDER_ONLY (its docblock now sits
on it; STRUCTURE stays in AttrWriter). Code of the pipeline moved unchanged.
- ValueCleaner's docblock is the one canonical description: steps 0-8 with their
  rulings in code order, invariants I1-I3; the step comments in cleanNode carry
  the same numbers. AttrWriter/ShortformWriter/Composer/TextReplacer docblocks
  point there and keep only their own rules.
- ValueCleaner::textReplacementFor($module) holds the D10 rule that was a
  closure in DiviReplaceTextAbility::replace (text/html only, clean() by kind).
- AttrWriter, ShortformWriter and Composer take the ValueCleaner; DiviComposition
  builds one per composition (cleaner()).
Tests: the eight AttrWriterTest methods that only exercised cleanValue/kindOf
moved verbatim to ValueCleanerTest (clean/kindOf, ComposeFixture::cleaner());
mixed tests call the cleaner in place; +1 test for textReplacementFor. Every
provider row and per-test assertion count unchanged.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01At3V6SjwbMe6eMzVGW3Hs7

src/Integrations/Divi/Pages/DiviContentComposer.php

@@ -29,8 +29,8 @@ use WP_Error;
  * (DiviWriter::composition). Should the entry's map refuse something (an option Divi offers
  * only for other types), write() returns the errors and lit/content-create deletes the draft.
  *
- * Every client string goes through Composer (AttrWriter / ShortformWriter) – the single choke
- * point that makes the kses bypass safe (spec D7).
+ * Every client string goes through Composer (AttrWriter / ShortformWriter → ValueCleaner) – the
+ * single choke point that makes the kses bypass safe (spec D7).
  */
 final class DiviContentComposer implements ContentComposer
 {