fix: post-flatten dev scripts, lead form validation, copy improvements

- Fix dev_run.sh and dev_setup.sh cd path (../.. after repo flatten)
- Quote form: re-render step 9 inline on validation error instead of
  flash + redirect to step 1; phone/email errors now show field-level
- Supplier FAQ: move differentiation Q to top, fix Q10 email to
  hello@ (was leads@), rename Q1 to "How do I get listed?"
- Replace Innenhalle → Indoorhalle throughout DE locale and seed script

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/scripts/dev_run.sh

@@ -10,7 +10,7 @@
 
 set -euo pipefail
 
-cd "$(dirname "$0")/.."
+cd "$(dirname "$0")/../.."
 
 # -- Colors & helpers --------------------------------------------------------