refactor(packages): dissolve ui/ and rename sdk/ to scaffold/

git mv per the regrouping RFC: the five human-collaboration seams and
tui join packages/interaction/, app-boot becomes packages/boot/, and
jsonrpc joins the renamed scaffold/ (formerly sdk/) as its server half
beside client/protocol/create-sdk/helper/scripts/telemetry, whose
folders drop the legacy sdk- prefix. Three new group README triplets
replace the ui/ and sdk/ ones; tsconfig references/paths/globs,
knip keys, vitest globs, gate scripts, catalogs, docs, and the
lockfile follow. Adds the four settled FIXME rename markers
(dsh-sdk-server, dsh-sdk-telemetry, dsh-sdk-helper, dsh-sdk-scripts).

The scaffold folders diverge from their npm names until those renames
land, so tsconfig.base.json maps the three affected names explicitly
beside the group wildcard. Also repairs two pre-existing stale-path
classes the strengthened sweep surfaced: docs/web-styling.md's retired
web-ui host package and type-model spec fixture-literal joins.

app-boot's three Loader-composition specs time out at the default 5s
under full-suite parallel load on this filesystem (pre-existing;
pass isolated with --testTimeout=30000); interaction/scaffold/boot
suites otherwise green (687 passed).

vitest.snapshot.config.ts

@@ -51,7 +51,7 @@ export default defineConfig({
       ...(process.env.DSH_EXAMPLE_MODE === 'lib' ? ['apps/web/tests/**/*.snapshot.ts'] : []),
       'apps/cli/tests/**/*.snapshot.ts',
       'examples/*/tests/**/*.snapshot.ts',
-      'packages/sdk/*/tests/**/*.snapshot.ts',
+      'packages/scaffold/*/tests/**/*.snapshot.ts',
     ],
     // Replay never writes committed outputs and every scenario owns its
     // mutable runtime state (the subprocess suites use a unique temp dir and