feat(signup): community guidelines agreement and policies routes

Introduces /community-guidelines and /policies/{privacy,terms,[slug]} pages,
swaps the signup/invite checkbox from agreedToTerms to agreedToGuidelines,
adds Member.agreement.acceptedAt, and stamps the field when a Helcim
customer is created.

app/pages/join.vue

@@ -65,7 +65,7 @@
         <ul>
           <li>Full access to the knowledge commons, Slack, and peer support</li>
           <li>Free access to all Ghost Guild events</li>
-          <li>One member, one vote</li>
+          <li>Equal access for every member, regardless of contribution</li>
           <li>Your circle reflects where you are, not rank</li>
           <li>Pay what you can ($0&ndash;$50+/month, separate from circle)</li>
           <li>Higher contributions create solidarity spots for others</li>
@@ -251,6 +251,20 @@
                   }"
                 />
               </div>
+              <div class="form-group full-width">
+                <label class="checkbox-label">
+                  <input
+                    v-model="form.agreedToGuidelines"
+                    type="checkbox"
+                  >
+                  <span>
+                    I agree to the Ghost Guild
+                    <NuxtLink to="/community-guidelines" target="_blank"
+                      >Community Guidelines</NuxtLink
+                    >.
+                  </span>
+                </label>
+              </div>
               <div class="form-group">
                 <button
                   class="form-submit"
@@ -264,9 +278,7 @@
               </div>
             </div>
             <p class="form-note">
-              By joining you agree to our
-              <NuxtLink to="/guidelines">community guidelines</NuxtLink>. You
-              can change your circle or contribution at any time from your
+              You can change your circle or contribution at any time from your
               dashboard. Payment is handled securely through
               <a href="https://www.helcim.com" target="_blank" rel="noopener"
                 >Helcim</a
@@ -397,6 +409,7 @@ const form = reactive({
   name: "",
   circle: "community",
   contributionTier: "15",
+  agreedToGuidelines: false,
   billingAddress: {
     street: "",
     city: "",
@@ -442,7 +455,13 @@ const {
 
 // Form validation
 const isFormValid = computed(() => {
-  return form.name && form.email && form.circle && form.contributionTier;
+  return (
+    form.name &&
+    form.email &&
+    form.circle &&
+    form.contributionTier &&
+    form.agreedToGuidelines
+  );
 });
 
 // Check if payment is required
@@ -471,6 +490,7 @@ const handleSubmit = async () => {
         email: form.email,
         circle: form.circle,
         contributionTier: form.contributionTier,
+        agreedToGuidelines: form.agreedToGuidelines,
         billingAddress: form.billingAddress,
       },
     });
@@ -961,6 +981,25 @@ onUnmounted(() => {
   color: var(--candle-dim);
 }
 
+/* ---- CHECKBOX ---- */
+.checkbox-label {
+  display: flex;
+  align-items: flex-start;
+  gap: 8px;
+  cursor: pointer;
+  font-size: 12px;
+  color: var(--text-dim);
+  line-height: 1.5;
+}
+.checkbox-label input {
+  margin-top: 3px;
+  flex-shrink: 0;
+}
+.checkbox-label a,
+.checkbox-label :deep(a) {
+  color: var(--candle);
+}
+
 /* ---- ERROR & SUCCESS BOXES ---- */
 .error-box {
   border: 1px dashed var(--ember);