Pre-install server deps for fast devcontainer start. Fix dev launch.json

There seems to be a more standard mechanism of specifying launch.json
params for devcontainers. Previous mechanism to write launch.json to
.vscode/launch.json in post creation step does not work.

Improve default launch.json to include khoj admin username, password
with placeholder values to get started with local development faster.

Define dockerfile for devcontainer to pre-built server, web app
dependencies during dev container image creation stage. So install on
dev container startup is sped up as no need to install dependencies.

scripts/dev_setup.sh

@@ -2,19 +2,14 @@
 # ---
 PROJECT_ROOT=$(git rev-parse --show-toplevel)
 
-# Default is a minimal, local installation unless config flags are set.
+# Default to minimal installation unless --full flag passed
 INSTALL_FULL=false
-DEVCONTAINER=false
 for arg in "$@"
 do
     if [ "$arg" == "--full" ]
     then
         INSTALL_FULL=true
     fi
-    if [ "$arg" == "--devcontainer" ]
-    then
-        DEVCONTAINER=true
-    fi
 done
 
 # Install Server App
@@ -28,7 +23,7 @@ python3 -m venv .venv && . .venv/bin/activate && python3 -m pip install -e '.[de
 # ---
 echo "Installing Web App..."
 cd $PROJECT_ROOT/src/interface/web
-yarn install
+yarn install && yarn export
 
 # Install Obsidian App
 # ---
@@ -46,74 +41,6 @@ if [ "$INSTALL_FULL" = true ] ; then
     yarn install
 fi
 
-# Create .vscode/launch.json if it doesn't exist
-# ---
-VSCODE_DIR="$PROJECT_ROOT/.vscode"
-LAUNCH_JSON_PATH="$VSCODE_DIR/launch.json"
-
-# Overwrite project vscode launch.json in devcontainer
-# ---
-# Differs from default launch.json with sudo true.
-# Required by pgserver in github codespaces, not in local dev.
-mkdir -p "$VSCODE_DIR"
-if [ "$DEVCONTAINER" = true ]; then
-  echo "Creating $LAUNCH_JSON_PATH..."
-  cat << EOF > "$LAUNCH_JSON_PATH"
-{
-    "version": "0.2.0",
-    "configurations": [
-        {
-            "name": "Launch Khoj",
-            "type": "debugpy",
-            "request": "launch",
-            "module": "src.khoj.main",
-            "justMyCode": false,
-            "console": "integratedTerminal",
-            "sudo": true,
-            "args": [
-                "-v",
-                "--anonymous-mode",
-                "--non-interactive",
-                "--port=42110",
-            ],
-            // You can load environment variables via a .env file, the env field below or Github Codespace secrets.
-            "envFile": "\${workspaceFolder}/.env",
-            "env": {
-                "KHOJ_ADMIN_EMAIL": "admin",
-                "KHOJ_ADMIN_PASSWORD": "admin",
-                "USE_EMBEDDED_DB": "True",
-                "KHOJ_DEBUG": "True",
-                "KHOJ_TELEMETRY_DISABLE": "True",
-                // Set LLM Provider API keys
-                // ---
-                // "GEMINI_API_KEY": "",
-                // "ANTHROPIC_API_KEY": "",
-                // "OPENAI_API_KEY": "",
-                // "OPENAI_BASE_URL": "http://localhost:11434/v1/",
-                // "KHOJ_DEFAULT_CHAT_MODEL": "claude-sonnet-4-0",
-                // Set Search Provider API keys
-                // ---
-                // "SERPER_DEV_API_KEY": "",
-                // "OLOSTEP_API_KEY": "",
-                // "FIRECRAWL_API_KEY": "",
-                // "JINA_API_KEY": "",
-                // Enable Khoj Operator
-                // ---
-                // "KHOJ_OPERATOR_ENABLED": "True",
-                // Configure Code Sandbox
-                // ---
-                // "KHOJ_TERRARIUM_URL": "http://localhost:8080",
-                // "E2B_API_KEY": "",
-                // Enable Promptracer to debug prompt flows
-                // ---
-                // "PROMPTRACE_DIR": "\${workspaceFolder}/promptrace",
-            }
-        },
-    ]
-}
-EOF
-fi
-
 # Install pre-commit hooks
 # ----
 echo "Installing pre-commit hooks..."