GitHub MCP Docker server missing REPO_OWNER/REPO_NAME environment variables

## Bug Report: GitHub MCP Docker server missing REPO_OWNER/REPO_NAME environment variables

### Description

The GitHub MCP server (Docker-based) does not receive `REPO_OWNER` and `REPO_NAME` environment variables, causing it to infer incorrect repository owner from GitHub App token metadata. This results in 404 errors when the GitHub App owner differs from the repository owner.

### Environment

- **Action Version**: `anthropics/claude-code-action@v1`
- **GitHub Environment**: GitHub Enterprise Server 3.17
- **MCP Server**: `ghcr.io/github/github-mcp-server` (Docker)
- **Authentication**: GitHub App (via `actions/create-github-app-token@v2`)

### Current Behavior

The action creates three MCP servers with **inconsistent** configuration:

1. ✅ **`github_inline_comment`** server (Bun-based):
```yaml
env:
REPO_OWNER: "ActualRepoOwner"
REPO_NAME: "example-repo"
```

2. ✅ **`github_ci`** server (Bun-based):
```yaml
env:
REPO_OWNER: "ActualRepoOwner"
REPO_NAME: "example-repo"
```

3. ❌ **`github`** MCP server (Docker-based):
```yaml
env:
GITHUB_PERSONAL_ACCESS_TOKEN: "***"
GITHUB_HOST: "https://ghe.company.com"
# MISSING: REPO_OWNER and REPO_NAME
```

### Expected Behavior

All three MCP servers should receive `REPO_OWNER` and `REPO_NAME` environment variables for consistency.

**Expected configuration for `github` server:**
```yaml
{
"github": {
"command": "docker",
"args": ["run", "-i", "--rm",
"-e", "GITHUB_PERSONAL_ACCESS_TOKEN",
"-e", "GITHUB_HOST",
"-e", "REPO_OWNER", // ← ADD THIS
"-e", "REPO_NAME", // ← ADD THIS
"ghcr.io/github/github-mcp-server:latest"],
"env": {
"GITHUB_PERSONAL_ACCESS_TOKEN": "***",
"GITHUB_HOST": "https://ghe.company.com",
"REPO_OWNER": "ActualRepoOwner", // ← ADD THIS
"REPO_NAME": "example-repo" // ← ADD THIS
}
}
}
```

### Impact

**Symptom**: GitHub MCP tools fail with 404 errors

**Affected Tools**:
- `mcp__github__get_pull_request`
- `mcp__github__get_pull_request_files`
- `mcp__github__get_pull_request_diff`
- Other `mcp__github__*` tools

**Error Pattern**:
```
API calls to: https://ghe.company.com/api/v3/repos/GitHubAppOwner/example-repo/pulls/123
^^^^^^^^^^^^^^^^
Wrong org inferred from GitHub App owner
Expected: https://ghe.company.com/api/v3/repos/ActualRepoOwner/example-repo/pulls/123
```

### Root Cause

When `REPO_OWNER` is not provided, the GitHub MCP Docker container infers the repository owner from the GitHub App installation token metadata.

**Scenario where this fails**:
- GitHub App is owned by organization "GitHubAppOwner"
- Repository is owned by organization "ActualRepoOwner"
- Docker container uses App owner ("GitHubAppOwner") instead of repo owner ("ActualRepoOwner")
- API calls fail with 404 errors

This is a common scenario in organizations that:
- Have multiple GitHub organizations
- Use a centralized GitHub App across organizations
- Use GitHub Enterprise with different org structures

### Steps to Reproduce

1. Create a GitHub App under organization A (e.g., "GitHubAppOwner")
2. Install the App in a repository under organization B (e.g., "ActualRepoOwner/example-repo")
3. Use `anthropics/claude-code-action@v1` with:
```yaml
- uses: actions/create-github-app-token@v2
with:
app-id: ${{ secrets.APP_ID }}
private-key: ${{ secrets.PRIVATE_KEY }}

- uses: anthropics/claude-code-action@v1
with:
github_token: ${{ steps.token.outputs.token }}
prompt: "Review PR"
```
4. Observe 404 errors when Claude attempts to use `mcp__github__*` tools

### Actual vs Expected Results

**Actual**:
- GitHub MCP server uses inferred owner from App token → "GitHubAppOwner"
- API calls: `GET /repos/GitHubAppOwner/example-repo/pulls/123` → **404 Not Found**

**Expected**:
- GitHub MCP server uses explicit `REPO_OWNER` → "ActualRepoOwner"
- API calls: `GET /repos/ActualRepoOwner/example-repo/pulls/123` → **200 OK**

### Workaround

Users can override the MCP configuration via `claude_args`:

```yaml
- name: Build MCP config
id: mcp_config
run: |
cat > /tmp/mcp-config.json <<'EOF'
{
"mcpServers": {
"github": {
"command": "docker",
"args": ["run", "-i", "--rm",
"-e", "GITHUB_PERSONAL_ACCESS_TOKEN",
"-e", "GITHUB_HOST",
"-e", "REPO_OWNER",
"-e", "REPO_NAME",
"ghcr.io/github/github-mcp-server:latest"],
"env": {
"REPO_OWNER": "${{ github.repository_owner }}",
"REPO_NAME": "${{ github.event.repository.name }}"
}
}
}
}
EOF
echo "config_file=/tmp/mcp-config.json" >> $GITHUB_OUTPUT

- uses: anthropics/claude-code-action@v1
with:
claude_args: --mcp-config ${{ steps.mcp_config.outputs.config_file }}
```

However, this requires workflow modifications and is not ideal.

### Suggested Fix

Update the GitHub MCP server configuration in the action to include `REPO_OWNER` and `REPO_NAME`, matching the pattern used for `github_inline_comment` and `github_ci` servers.

**Proposed code location**: Where the action constructs the MCP server configuration for the Docker-based GitHub server

**Proposed change**: Add environment variables similar to the Bun-based servers:
```typescript
// Existing pattern for github_inline_comment and github_ci
const repo_owner = context.repo.owner;
const repo_name = context.repo.repo;

// Apply same pattern to github Docker server
mcpServers.github = {
command: "docker",
args: [
"run", "-i", "--rm",
"-e", "GITHUB_PERSONAL_ACCESS_TOKEN",
"-e", "GITHUB_HOST",
"-e", "REPO_OWNER", // ← Add this
"-e", "REPO_NAME", // ← Add this
"ghcr.io/github/github-mcp-server:latest"
],
env: {
GITHUB_PERSONAL_ACCESS_TOKEN: token,
GITHUB_HOST: apiUrl,
REPO_OWNER: repo_owner, // ← Add this
REPO_NAME: repo_name // ← Add this
}
};
```

### Additional Context

This issue affects organizations using:
- GitHub Enterprise
- Multi-organization setups
- Centralized GitHub App installations
- Any scenario where App owner ≠ repository owner

### Related Information

- Similar configuration works correctly for `github_inline_comment` and `github_ci` servers
- The issue is specific to the Docker-based GitHub MCP server
- Docker container expects these variables to be passed via `-e` flags
- Without explicit variables, the container falls back to App token introspection