refactor: move libs/shared/src/ui/ into atoms/molecules/organisms (RD-27)

The folder now equals the layer, as CLAUDE.md decision 2 requires. 33
directories move by git mv (25 flat, plus upload/'s 8 subfolders split
across all three layers). 28 distinct @shared/ui/* specifiers rewrite
across 73 files, longest-first. Five relative imports inside upload/
become @shared/ui aliases because their sibling now lives in a
different layer; two stay relative because both ends stay in the same
layer. Four .mdx docs get their seven broken story imports fixed;
atomic-design.mdx's page-shell import is untouched, because layout/
does not move.

No component, template, story title, or layer-tag comment changes.
That is RD-28's job.

Verified against the ticket's acceptance commands: the 26 flat
directories become exactly 3 layer folders with the counts the ticket
names, only three @shared/ui/* prefixes remain (atoms, molecules,
organisms), the .mdx import count holds at 7, and the relative-import
count inside ui/ drops from 7 to 2 as decision 4 requires. The
@shared/ui/ occurrence count moves from 200 to 205: decision 4
mandates turning 5 of those 7 relative imports into @shared/ui/*
aliases, which decision 3's "200 before, 200 after" check does not
account for. The 5-occurrence gap is exactly the 5 conversions decision
4 names, not a lost or duplicated specifier.

npm run ci --full passes: lint, typecheck, dep:check, format, tokens,
seam, both apps' + both libraries' tests, both apps' localized build,
audit, backend tests, all three generated-artifact drift checks, and
both Storybook instances' build + axe-core a11y suite (67+45 suites,
198+112 tests, all green).

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

docs/project/readable-codebase/README.md

@@ -121,7 +121,7 @@ two. Note that RD-15 exists because 22 abandoned agent worktrees are still on di
 | RD-24 | `concepts.page` to 6 sections + `concept-card` + globals + code tokens       | 02         | yes       | done   |
 | RD-25 | `org-template-editor` to `sample-letter.ts` + labels + 2 children            | 02         | yes       | done   |
 | RD-26 | `letter-canvas`: inline the labels + `letter-line`; keep one disable         | 02         | yes       | done   |
-| RD-27 | **The layer move:** 33 `git mv` + 28 specifiers + 8 MDX imports              | 21         | yes       | todo   |
+| RD-27 | **The layer move:** 33 `git mv` + 28 specifiers + 8 MDX imports              | 21         | yes       | done   |
 | RD-28 | Layer-tag fixes + the `libs/beheer` title rule                               | 27         |           | todo   |
 | RD-29 | The 3 atomic-ladder rules in dependency-cruiser                              | 27         |           | todo   |
 | RD-30 | Archive the finished backlogs (16,300 lines) + an archive README             | 01         |           | todo   |