perf(diff): Pierre diff optimizations (#419)

* perf: implement virtualized rendering for diff viewer

- Enables efficient rendering of large diffs by only rendering visible content
- Uses shared virtualizer cache to optimize memory across multiple diff viewers
- Configures virtual scrolling with 24px line height for consistent layout

* fix: improve diff viewer line selection and annotation rendering

* fix: normalize line ranges to prevent selection bugs

* chore: upgrade @opencode-ai/sdk to v1.1.65

package.json

@@ -83,7 +83,7 @@
     "@ibm/plex": "^6.4.1",
     "@lezer/highlight": "^1.2.3",
     "@octokit/rest": "^22.0.1",
-    "@opencode-ai/sdk": "^1.1.53",
+    "@opencode-ai/sdk": "^1.1.65",
     "@radix-ui/react-collapsible": "^1.1.12",
     "@radix-ui/react-dialog": "^1.1.15",
     "@radix-ui/react-dropdown-menu": "^2.1.16",