feat: add project channel workbench shell

apps/web/src/features/workbench/ProjectChannelSidebar.svelte

@@ -0,0 +1,52 @@
+<script lang="ts">
+  import type { AISessionItem, WorkbenchChannel, WorkbenchProject } from './types';
+
+  export let project: WorkbenchProject;
+  export let channels: WorkbenchChannel[];
+  export let selectedChannelID: string;
+  export let tags: string[];
+  export let recentSessions: AISessionItem[];
+  export let onSelectChannel: (channelID: string) => void;
+</script>
+
+<aside class="channel-sidebar" aria-label="Project channels">
+  <header>
+    <div>
+      <p>Current project</p>
+      <h2>{project.name}</h2>
+    </div>
+    <button aria-label="Project settings">&#9881;</button>
+  </header>
+
+  <section class="tag-row" aria-label="Project tags">
+    {#each tags as tag}
+      <button type="button">#{tag}</button>
+    {/each}
+  </section>
+
+  <section class="channel-group">
+    {#each channels as channel}
+      <button
+        class:active={channel.id === selectedChannelID}
+        aria-pressed={channel.id === selectedChannelID}
+        aria-label={`${channel.title}${channel.count ? ` ${channel.count}` : ''}`}
+        on:click={() => onSelectChannel(channel.id)}
+      >
+        <span>{channel.title}</span>
+        {#if channel.count !== undefined}
+          <small>{channel.count}</small>
+        {/if}
+      </button>
+    {/each}
+  </section>
+
+  <section class="recent-sessions" aria-label="Recent sessions">
+    <h3>Recent sessions</h3>
+    {#each recentSessions as session}
+      <button type="button">
+        <span>{session.title}</span>
+        <small>{session.updatedAt}</small>
+      </button>
+    {/each}
+  </section>
+</aside>