Backend module: CSV import for the VITEC domain models

New "VITEC Import" module under Web: one import page per domain model
(v1: Market, Solution, Product - registry-driven, adding a model is one
config entry). Workflow: upload a CSV (delimiter and encoding are
auto-detected, including German-Excel semicolon/Windows-1252), map CSV
columns to DB fields, persist the mapping per model together with the
identity field used for matching (new table tx_vitec_import_mapping,
no TCA - pure tool configuration), review a unified list of CSV rows
matched against the DB records (new / update with differing fields /
unchanged / db-only), then apply the checked rows through DataHandler.

Each importable row carries an editable JSON payload textarea - what
is written is the textarea content, not the raw CSV, so editors can
fix values right in the review step. The parsed CSV travels through
the form as a hidden JSON field: no session state, no temp files.
Importable fields are derived from TCA at runtime (scalar types only;
files, categories and other relations are excluded - a flat CSV
cannot carry them). Payloads are whitelisted against that field list
on apply; new records require a storage pid (prefilled from existing
records). BE user permissions apply via DataHandler.

The module ships its own CSS (backend-import.css, loaded only by
this module) using the frontend button palette from _vitec.scss:
orange #f47937 for primary actions, navy #26358c for secondary
actions and structure. The stray <h2>Hi</h2> debug leftover in the
shared backend layout is removed (also affects the OG Image module).

Deliberately out of v1: import log with three-way compare (protection
against overwriting manual edits), images/relations, multiple saved
mappings per model.

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

packages/vitec/Resources/Private/Layouts/Backend/Default.html

@@ -2,7 +2,6 @@
       xmlns:n="http://typo3.org/ns/GeorgRinger/News/ViewHelpers">
 <div class="vitec-administration">
 	<f:flashMessages queueIdentifier="core.template.flashMessages" />
-    <h2>Hi</h2>
 	<f:render section="main"/>
 </div>
 </html>