fix(ui): make asset build source deterministic

docs/tests/web/review-round-1-shared-ui.md

@@ -48,6 +48,8 @@ Following the Admin shell's visible /profile link returned 404 instead of 200.
 After the four reviewed producer pins were merged, the three producer WebMvc slices ran 39 tests with 39 context errors. The merged Platform SmtpWarningAdvice required SmtpConfigurationService, which was absent only from those narrow slice fixtures; no behavior assertion ran.
 
 The collapsed-sidebar regression failed 1/1 at the missing aria-expanded assertion. The favicon regression failed 1/1 because the rendered shared shell had no explicit local icon link; the real browser independently logged /favicon.ico as 404.
+
+The first post-Maven deterministic asset check changed app.css because Tailwind automatic source discovery included generated target output; a generated ring token changed the production bundle without any source-template change.
 BUILD FAILURE
 ```
 
@@ -94,9 +96,11 @@ npm run build
 
 Node v24.19.0; npm 11.17.0
 Tailwind CSS v4.3.3: Done
+Two consecutive builds produced app.css SHA-256 7bd351d0f2cae97af70532e8ee0e0248265782b508d378fd7c277cbb4f373946 and icons.svg SHA-256 001f72c93967f816fdd56f3f9b34cb5e5831b8b8c572d051669c6a3aae2c3cda.
 Merged affected web suite on PostgreSQL 18.4: Tests run: 79, Failures: 0, Errors: 0, Skipped: 0
+Full PostgreSQL 18.4 suite: Tests run: 195, Failures: 0, Errors: 0, Skipped: 0
 Compile: success
-Javadoc/doclint: success
+Full Javadoc/doclint: success (producer-owned missing-comment warnings remain non-fatal)
 BUILD SUCCESS
 ```
 

src/main/frontend/app.css

@@ -1,4 +1,4 @@
-@import "tailwindcss";
+@import "tailwindcss" source(none);
 @source "../resources/templates/**/*.html";
 
 @theme {