refactor: migrate LangGraph server from Container App to Azure Web App

## Changes
- Delete Dockerfile and .dockerignore (no longer needed)
- Rewrite deploy-langgraph.yml: zip deploy to Web App (not ACR build)
- Update deploy-langgraph-ui.yml: VITE_LANGGRAPH_URL → soc-langgraph.azurewebsites.net

## Azure Resources
- CREATED: soc-langgraph Web App (Node.js 20, B1 Linux, southeastasia)
- CREATED: soc-langgraph-plan (App Service Plan, B1, southeastasia)
- DELETED: soc-langgraph Container App
- DELETED: soc-cae Container App Environment
- DELETED: socsocacr ACR
- All env vars migrated to Web App
- Startup: npx langgraphjs dev --host 0.0.0.0 --port 2024 --no-browser
- WEBSITES_PORT=2024

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

langgraph/.dockerignore

@@ -1,6 +0,0 @@
-node_modules
-.git
-dist
-.env
-*.local
-.DS_Store

langgraph/Dockerfile

@@ -1,26 +0,0 @@
-FROM node:20-slim
-
-# Install pnpm
-RUN npm install -g pnpm@10
-
-WORKDIR /app
-
-# Copy package files and install dependencies
-COPY package.json pnpm-lock.yaml ./
-RUN pnpm install --frozen-lockfile
-
-# Copy source code
-COPY . .
-
-# langgraphjs dev requires .env to exist, and writes .langgraph_api + .gitignore on startup
-# Pre-create these to prevent tsx file watcher from triggering a restart loop
-RUN touch .env && \
-    mkdir -p .langgraph_api && \
-    echo ".langgraph_api" >> .gitignore
-
-# Expose LangGraph server port
-EXPOSE 2024
-
-# Use langgraphjs dev with explicit host binding
-# The --host flag ensures it binds to 0.0.0.0 not just localhost
-CMD ["pnpm", "exec", "langgraphjs", "dev", "--host", "0.0.0.0", "--port", "2024", "--no-browser"]