feat: vscode extension (#59)

* feat: add initial VS Code extension plan and implementation tasks

* feat(vscode): added initial version of an Openchamber VSCode extension

* feat(vscode): enhance VS Code extension with theme integration and session management

* feat(vscode): implement connection status handling and overlay in VSCode layout

* feat: move extension to secondary sidebar

* chore: upgrade @opencode-ai/sdk to 1.0.150

* vscode: editor bridge, file picker, click-to-open in tool parts

* vscode: layout session lifecycle, theme sync, typography overrides

* ui: compact mode for vscode, model search, autocomplete width fixes

* perf: scroll force flag, raf placeholder, git polling backoff

* ui: tool output styling, markdown code block fix, gitignore

* refactor: update typography handling for VSCode runtime, remove unused styles

* docs: update README with VS Code extension details and add extension image

* docs: update changelog with new features and performance improvements

packages/vscode/assets/app-icon-checkpoint.svg

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg width="1024" height="1024" viewBox="0 0 1024 1024" xmlns="http://www.w3.org/2000/svg">
+  <!-- Dark rounded background -->
+  <rect x="0" y="0" width="1024" height="1024" rx="150" ry="150" fill="#1a1616"/>
+
+  <!-- Glyph centered -->
+  <g transform="translate(512, 512) scale(10) translate(-35, -36.5)">
+    <path fill-rule="evenodd" clip-rule="evenodd" d="M0 13H35V58H0V13ZM26.25 22.1957H8.75V48.701H26.25V22.1957Z" fill="#F8F7F3"/>
+    <rect x="8.75" y="30" width="17.5" height="18.5" fill="#4B4646"/>
+    <path d="M43.75 13H70V22.1957H52.5V48.701H70V57.8967H43.75V13Z" fill="#F8F7F3"/>
+  </g>
+</svg>

packages/vscode/assets/icon.svg

@@ -0,0 +1,9 @@
+<svg width="24" height="24" viewBox="0 0 70 70" xmlns="http://www.w3.org/2000/svg">
+  <g transform="translate(35, 35) scale(0.95) translate(-35, -35)">
+    <path fill-rule="evenodd" clip-rule="evenodd"
+          d="M0 13H35V58H0V13ZM26.25 22.1957H8.75V48.701H26.25V22.1957Z"
+          fill="#808080"/>
+    <path d="M43.75 13H70V22.1957H52.5V48.701H70V57.8967H43.75V13Z"
+          fill="#808080"/>
+  </g>
+</svg>