`resolveDiscoveredConfig` does not read workspace `.mcp.json` — `includeWorkspaceSources` never set

## Summary

When the SDK creates a session with `enableConfigDiscovery: true` and a `workingDirectory`, the CLI's `resolveDiscoveredConfig()` calls the internal MCP config loader (`jv()`) **without** passing `includeWorkspaceSources: true`. That parameter defaults to `false`, so the workspace `.mcp.json` is never read — even though the intent of `enableConfigDiscovery` is clearly to discover it.

## Version

`@github/copilot` v1.0.41-0 (commit `3f18c2c`)

## Steps to reproduce

1. Place a valid `.mcp.json` in a working directory:
```json
{
"mcpServers": {
"time": {
"command": "uvx",
"args": ["mcp-server-time"]
}
}
}
```
2. Create a session via the SDK with `enableConfigDiscovery: true` and `workingDirectory` pointing to that directory.
3. Observe that no MCP servers from `.mcp.json` are discovered.

## Expected behaviour

The MCP servers defined in the workspace `.mcp.json` should be discovered and loaded into the session.

## Actual behaviour

The CLI logs:
```
Loaded MCP config from installed plugins: 0 server(s):
No MCP config loaded from ODR (ODR unavailable or returned no usable servers)
```

No workspace `.mcp.json` is read. The flag triggers config resolution, but the resolution skips the workspace source.

## Root cause

In `resolveDiscoveredConfig()`, the call to `jv()` omits `includeWorkspaceSources`:

```js
async resolveDiscoveredConfig(e) {
if (!e.enableConfigDiscovery) return {};
let r = e.workingDirectory || process.cwd();
// ...
let c = await jv({
cwd: r,
repoRoot: l,
settings: this.options.settings,
installedPlugins: s
// ← missing: includeWorkspaceSources: true
});
}
```

Inside `jv()`, the parameter defaults to `false`. When false, the function skips the code path that reads `.mcp.json` from the working directory:

```js
async function jv(t = {}) {
let { includeWorkspaceSources: s = false } = t;
// ...
if (!s) d = { ...c }; // ← only copies global config
else {
// reads .mcp.json from cwd/repoRoot — this path is never taken
}
}
```

## Suggested fix

Pass `includeWorkspaceSources: true` in the `jv()` call within `resolveDiscoveredConfig()`:

```js
let c = await jv({
cwd: r,
repoRoot: l,
settings: this.options.settings,
installedPlugins: s,
includeWorkspaceSources: true // ← add this
});
```