harden: drop 'unsafe-inline' from style-src (closes #328)

The popup's markup no longer carries style attributes. The 42 in
index.html and in the HTML the view helpers build are now Tailwind
classes, each computing to the value it replaced, so style-src is 'self'
in both manifests, pinned in tests/manifest.test.js.

The address dot's 16 colours are written out as whole classes, because
Tailwind builds only the classes it finds in the source. The Settings
debug well is shown and hidden with the hidden class, since clearing an
inline display no longer uncovers it. Two tests that found the colour dot
by its inline style now find it by its class. Script that sets
element.style is unaffected.

Model: opus-5-5

tests/manifest.test.js

@@ -21,15 +21,14 @@
 // escaping in src/shared/html.js is the primary fix; default-src is what
 // stops the next escape that slips from reaching the network.
 //
-// Every directive below is pinned exactly, because each of the four
+// And for #328: style-src is 'self' alone, so the browser refuses every
+// style="..." attribute in the popup's markup, including one an escape lets
+// through. The popup styles with classes; script setting element.style is
+// not affected.
+//
+// Every directive below is pinned exactly, because each of the three
 // loosenings is load-bearing and none of them may grow:
 //
-//   style-src 'unsafe-inline'  src/popup/index.html and the view helpers
-//                              use style="..." attributes throughout, which
-//                              CSP blocks without it. Chrome enforces this
-//                              on attributes, not just <style> blocks, and
-//                              Firefox has never implemented style-src-attr,
-//                              so there is no narrower spelling available.
 //   img-src data:              blockies are data: PNGs assigned to img.src.
 //   connect-src https: http:   the RPC endpoint is user-configurable, and a
 //                              local node over http://127.0.0.1 is a
@@ -58,7 +57,7 @@ const EXPECTED_DIRECTIVES = {
     "default-src": ["'self'"],
     "script-src": ["'self'", "'wasm-unsafe-eval'"],
     "object-src": ["'self'"],
-    "style-src": ["'self'", "'unsafe-inline'"],
+    "style-src": ["'self'"],
     "img-src": ["'self'", "data:"],
     "connect-src": ["'self'", "http:", "https:"],
     "frame-src": ["'none'"],