feat(devcontainer): add GitHub Codespaces configuration (#6801)

* feat(devcontainer): add Codespaces config with Claude Code and Vale

Adds GitHub Codespaces / devcontainer configuration:
- Node.js 20 base image with Hugo extended
- Auto-installs: yarn dependencies, Vale CLI, Claude Code CLI
- VS Code extensions: Markdown, Prettier, YAML, Vale
- Port forwarding for Hugo dev server (1313)
- Secrets prompt for ANTHROPIC_API_KEY

Usage:
1. Open repo in Codespaces
2. Add ANTHROPIC_API_KEY to Codespaces secrets
3. Run `claude` to start Claude Code with full network access

https://claude.ai/code/session_0173AuWPoy6UXiatCMGz4W7h

* fix(devcontainer): remove invalid secrets field, use latest Hugo

- Remove 'secrets' field (not valid in devcontainer schema, configure in GitHub settings)
- Remove specific Hugo version (use feature default)
- Add codespaces.openFiles for better UX

https://claude.ai/code/session_0173AuWPoy6UXiatCMGz4W7h

* fix(devcontainer): simplify config, remove docker-in-docker

- Remove docker-in-docker feature (may cause filesystem provider errors)
- Remove codespaces-specific settings
- Simplify extensions list
- Make setup.sh more resilient (don't fail on warnings)

https://claude.ai/code/session_0173AuWPoy6UXiatCMGz4W7h

---------

Co-authored-by: Claude <noreply@anthropic.com>

.devcontainer/devcontainer.json

@@ -0,0 +1,30 @@
+{
+  "name": "InfluxData Docs",
+  "image": "mcr.microsoft.com/devcontainers/javascript-node:20",
+
+  "features": {
+    "ghcr.io/devcontainers/features/hugo:1": {
+      "extended": true
+    }
+  },
+
+  "postCreateCommand": "bash .devcontainer/setup.sh",
+
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "yzhang.markdown-all-in-one",
+        "esbenp.prettier-vscode",
+        "redhat.vscode-yaml"
+      ],
+      "settings": {
+        "editor.formatOnSave": true,
+        "[markdown]": {
+          "editor.wordWrap": "on"
+        }
+      }
+    }
+  },
+
+  "forwardPorts": [1313]
+}

.devcontainer/setup.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+
+echo "Setting up InfluxData Docs development environment..."
+
+# Install project dependencies
+echo "Installing Node.js dependencies..."
+yarn install || echo "Warning: yarn install had issues"
+
+# Install Vale CLI
+echo "Installing Vale linter..."
+VALE_VERSION="3.12.0"
+curl -sfL "https://github.com/errata-ai/vale/releases/download/v${VALE_VERSION}/vale_${VALE_VERSION}_Linux_64-bit.tar.gz" | tar -xz -C /tmp
+sudo mv /tmp/vale /usr/local/bin/vale 2>/dev/null || mv /tmp/vale ~/bin/vale
+chmod +x /usr/local/bin/vale 2>/dev/null || chmod +x ~/bin/vale
+
+# Sync Vale styles
+echo "Syncing Vale styles..."
+vale sync 2>/dev/null || echo "Vale sync skipped (styles exist locally)"
+
+# Install Claude Code CLI
+echo "Installing Claude Code CLI..."
+npm install -g @anthropic-ai/claude-code || echo "Warning: Claude Code install had issues"
+
+# Verify installations
+echo ""
+echo "✅ Setup complete! Installed versions:"
+echo "   Node.js: $(node --version)"
+echo "   Yarn: $(yarn --version)"
+echo "   Hugo: $(hugo version | head -1)"
+echo "   Vale: $(vale --version)"
+echo "   Claude Code: $(claude --version 2>/dev/null || echo 'installed (run claude to authenticate)')"
+
+echo ""
+echo "🚀 Quick start commands:"
+echo "   hugo server          # Start dev server on port 1313"
+echo "   vale content/        # Run style linter"
+echo "   claude               # Start Claude Code CLI"
+echo ""
+echo "💡 Tip: Set ANTHROPIC_API_KEY in Codespaces secrets for Claude Code"