Drop 'unsafe-inline' from the Content-Security-Policy (closes #530)

The delete prompts on the webhook page were inline onsubmit handlers.
Each delete form now carries its question in a data-confirm attribute,
which one submit listener in static/js/app.js asks. The three style
attributes became Tailwind classes, with tailwind.css regenerated, and
the x-cloak rule moved to style.css. The policy now sends
script-src 'self' and style-src 'self'.

The browser test now answers a target's delete prompt no and then yes,
and also loads the sign-in page, the webhook list, the settings and
profile pages and the 404 error page under the policy. The README
states the policy as sent.

Model: opus-5-5

internal/handlers/event_detail_test.go

@@ -84,7 +84,7 @@ func TestHandleEventDetail_ShowsEventWholeWithDeliveries(t *testing.T) {
 	assert.Contains(t, page, strconv.Itoa(len(body))+" bytes")
 	assert.Contains(t, page, "{\n  "pad": "xxx")
 	assert.Contains(t, page, ""tail": ""+sentinel+""\n}")
-	assert.Contains(t, page, `style="max-height: 32rem; overflow-y: auto"`)
+	assert.Contains(t, page, `break-all max-h-[32rem] overflow-y-auto"`)
 	assert.NotContains(t, page, "Showing the first")
 	assert.Contains(t, page, target.Name)
 	assert.Contains(t, page, ">failed</span>")