feat: add VS Code configuration for debugging bun

- Add .vscode/extensions.json recommending oven.bun-vscode.
- Add .vscode/launch.json with Bun debug configurations for various scripts.
- Add .vscode/settings.json for TypeScript SDK, debug options, and file exclusions.
- Remove .vscode/ entry from .gitignore.
- Refactor ingest.ts: increase chunk size to 8192 and overlap to 200, raise large document threshold, remove <h1>/<h2> separators, skip sections containing only headings or minimal content, and add warnings for very small chunks.

.vscode/launch.json

@@ -0,0 +1,52 @@
+{
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "name": "Debug: Agent",
+      "type": "bun",
+      "request": "launch",
+      "program": "${workspaceFolder}/agent.ts",
+      "args": ["How does array DefineOwnProperty work?"],
+      "cwd": "${workspaceFolder}",
+      "stopOnEntry": false,
+      "watchMode": false
+    },
+    {
+      "name": "Debug: Ingest",
+      "type": "bun",
+      "request": "launch",
+      "program": "${workspaceFolder}/setup/ingest.ts",
+      "cwd": "${workspaceFolder}",
+      "stopOnEntry": false,
+      "watchMode": false
+    },
+    {
+      "name": "Debug: Test Spec Retriever",
+      "type": "bun",
+      "request": "launch",
+      "program": "${workspaceFolder}/test/manual/test-spec-retriever.ts",
+      "args": ["array.[[DefineOwnProperty]]"],
+      "cwd": "${workspaceFolder}",
+      "stopOnEntry": false,
+      "watchMode": false
+    },
+    {
+      "name": "Debug: Build Graph",
+      "type": "bun",
+      "request": "launch",
+      "program": "${workspaceFolder}/setup/build_graph.ts",
+      "cwd": "${workspaceFolder}",
+      "stopOnEntry": false,
+      "watchMode": false
+    },
+    {
+      "name": "Debug Current File",
+      "type": "bun",
+      "request": "launch",
+      "program": "${file}",
+      "cwd": "${workspaceFolder}",
+      "stopOnEntry": false,
+      "watchMode": false
+    }
+  ]
+}