Fix deployment_environment default so the debugger reads UAT

project.godot's API URLs already pointed at UAT (us3q.ranaze.com), but
deployment_environment itself was still "development" - a leftover
label that never matched the actual origin. Since the UAT-only feature
gates (Dynamic Questions, CCS Cases, Flashcards) check for the literal
"uat" value, running from the Godot editor/debugger hid all three even
though it's UAT in every other respect.

Set it to "uat" to match reality, and update the two places that
sed-patch this value at build time (web/Dockerfile for the UAT/PRD web
builds, tools/export_steam_release.sh for the Steam build) so they
still match the source string they're replacing.

web/Dockerfile

@@ -32,7 +32,7 @@ WORKDIR /src
 COPY . .
 RUN mkdir -p /build \
     && sed -i "s|build_revision=\"development\"|build_revision=\"${BUILD_REVISION}\"|" project.godot \
-    && sed -i "s|deployment_environment=\"development\"|deployment_environment=\"${DEPLOYMENT_ENVIRONMENT}\"|" project.godot \
+    && sed -i "s|deployment_environment=\"uat\"|deployment_environment=\"${DEPLOYMENT_ENVIRONMENT}\"|" project.godot \
     && sed -i "s|https://us3q.ranaze.com|${PUBLIC_API_ORIGIN}|g" project.godot \
     && sed -i "s|custom_template/release=\"\"|custom_template/release=\"/root/.local/share/godot/export_templates/${GODOT_TEMPLATE_DIR}/web_nothreads_release.zip\"|" export_presets.cfg \
     && godot --headless --editor --path /src --quit \