Phase 4: web markers and JourneyMap/Xaero waypoint chat sharing

Linked accounts can place 2D markers on the map (y auto-derived from the
chunk store's heightmap); anonymous visitors keep a localStorage-only
list via the same height lookup. Sharing a marker forwards a structured
payload to the mod over its WS connection, which builds the actual
chat text (see MCMapper-Mod for the JourneyMap/Xaero formatting).

Built test-first per the project's TDD workflow.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015tKdPZt78zbPUZMXWzKEKt

frontend/src/views/index.pug

@@ -23,6 +23,36 @@ html(lang="en")
       div.flex-1.flex.overflow-hidden
         div#map.flex-1
         aside.w-80.flex.flex-col.border-l.border-neutral-700.bg-neutral-800(x-show="server")
+          div.border-b.border-neutral-700.p-2.space-y-2(style="max-height: 40%; overflow-y: auto;")
+            div.flex.items-center.justify-between
+              h2.text-sm.font-semibold Markers
+              button.px-2.py-1.rounded.text-xs(
+                x-bind:class="placingMarker ? 'bg-amber-600' : 'bg-neutral-700'"
+                x-on:click="togglePlacingMarker"
+                x-text="placingMarker ? 'click the map…' : '+ place marker'")
+
+            template(x-if="pendingMarker")
+              div.space-y-1.bg-neutral-900.rounded.p-2
+                p.text-xs.text-neutral-400(x-text="'at ' + pendingMarker.x + ', ' + pendingMarker.z")
+                div.flex.gap-1
+                  input.flex-1.bg-neutral-800.text-sm.px-2.py-1.rounded.border.border-neutral-700(
+                    type="text" placeholder="marker name" x-model="markerNameInput"
+                    x-on:keydown.enter="confirmMarker")
+                  input.w-10(type="color" x-model="markerColorInput")
+                div.flex.gap-1
+                  button.flex-1.px-2.py-1.bg-emerald-700.rounded.text-xs(x-on:click="confirmMarker") Save
+                  button.px-2.py-1.bg-neutral-700.rounded.text-xs(x-on:click="cancelMarker") Cancel
+
+            template(x-for="marker in markers" x-bind:key="marker.id")
+              div.flex.items-center.gap-2.text-sm
+                span.inline-block.w-3.h-3.rounded-full.flex-shrink-0(x-bind:style="'background:' + marker.color")
+                span.flex-1.truncate(x-text="marker.name")
+                span.text-xs.text-neutral-500(x-text="marker.x + ', ' + marker.y + ', ' + marker.z")
+                button.text-xs.underline(x-show="account" x-on:click="shareMarker(marker)") share
+                button.text-xs.text-red-400(x-on:click="deleteMarker(marker)") ×
+
+            p.text-xs.text-amber-400(x-show="markerStatus" x-text="markerStatus")
+
           div.flex-1.overflow-y-auto.p-2.space-y-1(x-ref="chatLog")
             template(x-for="msg in chatMessages" x-bind:key="msg.id")
               p.text-sm.break-words
@@ -57,4 +87,4 @@ html(lang="en")
                 button.px-2.py-1.bg-neutral-700.rounded.text-sm(x-on:click="redeemLink") Link
 
             p.text-xs.text-amber-400(x-show="linkStatus" x-text="linkStatus")
-    script(src="/js/map.js")
+    script(type="module" src="/js/map.js")