Trim dead code and tighten the branch to surgical scope

- palette-picker.js: drop the superseded APP/DOCS/INDEX copy tables, the
  disabled font-rail hoist machinery, LOREM.caption, and an orphan marker
- design-context.css + dcx-hierarchy.css: drop the demo-era specimen,
  radius, and spacing-bar rule groups nothing renders
- index.astro: drop an unreferenced boards const
- de-export module-internal names (store, bindings, portability,
  visual-cues); remove picker-server's unused doc-session kill switch and
  document --doc in its help
- palette.mjs: realpath the entry guard so symlinked installs still run
  the CLI (same guard as visual-cues.mjs)
- revert serve-question.mjs copy ride-along; drop the plan/ gitignore
  entry; dedupe a build-picker comment; file design-context with the
  system category entries; alphabetize IMPECCABLE_SUB_COMMANDS
- new-work.md: drop a same-screen restatement of the comp/world ranking
- CLAUDE.md: correct the picker gate baseline to the measured 606 and
  explain the per-element multiplication; the trims removed the two
  dead-block font findings
- DESIGN-CONTEXT-ARCHITECTURE.md: list portability.mjs in the code layout

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

skill/scripts/visual-cues.mjs

@@ -40,7 +40,7 @@ function paeth(a, b, c) {
   return c;
 }
 
-export function decodePng(buf) {
+function decodePng(buf) {
   if (!buf.subarray(0, 8).equals(PNG_SIG)) throw new Error('not a PNG file');
   // Walk the chunk stream: each chunk is [4-byte length][4-byte type][data][4-byte crc].
   // IHDR carries the header fields; IDAT is the (possibly multi-chunk)
@@ -306,8 +306,8 @@ function main() {
 }
 
 // Only auto-run when invoked directly (`node visual-cues.mjs ...`), not
-// when another module imports its exports (decodePng, etc.), e.g. from a
-// test file. import.meta.url is Node's realpath of the entry file, so
+// when another module imports it. import.meta.url is Node's realpath of
+// the entry file, so
 // argv[1] must be realpath'd too, not just path.resolve'd: a skill
 // installed via symlink (the standard `skills link`/install path) makes
 // argv[1] the symlink path, which never equality-matches the resolved