feat: padlock toolbar icon with spiral keyhole

icons/passchmop.svg

@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 128 128">
+  <title>Passchmop</title>
+  <!--
+    Shackle, two-tone: a thick dark outer stroke + a light silver inner
+    stroke along the same path produces a silver arc with a dark border.
+    Light silver pops on dark toolbars; the dark border pops on light.
+  -->
+  <path d="M 40 64 V 40 A 24 24 0 0 1 88 40 V 64"
+        fill="none" stroke="#1a1d24" stroke-width="24" stroke-linecap="round"/>
+  <path d="M 40 64 V 40 A 24 24 0 0 1 88 40 V 64"
+        fill="none" stroke="#e4e7ec" stroke-width="14" stroke-linecap="round"/>
+
+  <!-- Body: saturated amber + thick dark outline. -->
+  <rect x="10" y="56" width="108" height="68" rx="14"
+        fill="#f4b942" stroke="#1a1d24" stroke-width="7"/>
+
+  <!--
+    Spiral keyhole, 1.5 turns. Each half-arc has radius = half chord, so
+    it's a semicircle; successive chords shrink, so the alternating
+    semicircles trace a clean spiral inward. Outer radius 22 fills most
+    of the body width for visibility at small sizes.
+  -->
+  <path d="M 86 90
+           A 18.5 18.5 0 0 1 49 90
+           A 11 11 0 0 1 71 90
+           A 3.5 3.5 0 0 1 64 90"
+        fill="none" stroke="#1a1d24" stroke-width="11"
+        stroke-linecap="round" stroke-linejoin="round"/>
+</svg>

manifest.json

@@ -3,6 +3,11 @@
   "name": "Passchmop",
   "version": "0.1.0",
   "description": "Git-backed, client-side-encrypted password manager.",
+  "icons": {
+    "48": "icons/passchmop.svg",
+    "96": "icons/passchmop.svg",
+    "128": "icons/passchmop.svg"
+  },
   "background": {
     "scripts": ["build/background.js"]
   },
@@ -10,7 +15,12 @@
   "host_permissions": ["https://*/*"],
   "action": {
     "default_title": "Passchmop",
-    "default_popup": "src/popup/popup.html"
+    "default_popup": "src/popup/popup.html",
+    "default_icon": {
+      "16": "icons/passchmop.svg",
+      "32": "icons/passchmop.svg",
+      "48": "icons/passchmop.svg"
+    }
   },
   "options_ui": {
     "page": "src/options/options.html",