[BUG] [Narratives/MCP] - compliance_batch_populate_narratives returns INVALID_INPUT for system_id even when systemId provided — parameter not passed to tool

## Bug Description

`compliance_batch_populate_narratives` returns `INVALID_INPUT: The 'system_id' parameter is required` even when:
1. A valid `systemId` is provided in the `/mcp/chat` request body
2. The system name ("Coastal Watch") is included explicitly in the message
3. The system resolves correctly for single-system operations (e.g., `compliance_get_system` successfully returns Coastal Watch data)

This is a **different failure mode** from the previously tracked bug (#537), which returned "no SSP baseline found / document service lookup failure." The system_id is now not reaching the batch tool at all — it fails at the parameter validation layer before attempting any lookup.

## Steps to Reproduce

```bash
BASE="https://ca-ato-copilot-mcp-v2.blackwater-9393aa1a.centralus.azurecontainerapps.io"

# Test 1: With systemId in request body
curl -s -X POST -H 'Content-Type: application/json' \
-d '{"message":"Auto-fill missing narratives for Coastal Watch","systemId":"92afdc15-bc6f-4648-8073-ad6af396cf97"}' \
"$BASE/mcp/chat"

# Test 2: System name in message only
curl -s -X POST -H 'Content-Type: application/json' \
-d '{"message":"auto-populate implementation narratives for Coastal Watch system"}' \
"$BASE/mcp/chat"
```

Both return:
```json
{"status":"error","errorCode":"INVALID_INPUT","message":"The 'system_id' parameter is required."}
```

## Expected Behavior

When a valid `systemId` is provided in the request body, or when the system name resolves unambiguously, `compliance_batch_populate_narratives` should receive the resolved `system_id` and proceed to populate narratives (even if it subsequently fails on SSP lookup — that is a separate issue).

## Actual Behavior

The batch populate narratives tool fails with `INVALID_INPUT` before any system lookup occurs. The `systemId` field from the request body is not being passed as `system_id` to the `compliance_batch_populate_narratives` tool parameters.

## Relationship to Existing Issues

- **#537** — Previous failure was `"no SSP baseline found"` (tool received system_id but couldn't find the document). This sweep shows the failure now occurs earlier — at parameter injection layer. Either the fix for the disambiguation routing broke the parameter pass-through, or this is a separate regression.

## Browser/Environment

MCP API: `https://ca-ato-copilot-mcp-v2.blackwater-9393aa1a.centralus.azurecontainerapps.io`
Endpoint: `POST /mcp/chat`
System under test: Coastal Watch (ID: `92afdc15-bc6f-4648-8073-ad6af396cf97`)
Date: 2026-06-30T08:01:11Z
Sweep: Automated 4-hour QA Sweep

## Playwright Test Code

```typescript
test('[Narratives] batch_populate_narratives receives system_id from chat context', async ({ request }) => {
const res = await request.post(`${BASE}/mcp/chat`, {
data: {
message: 'auto-populate narratives for Coastal Watch',
systemId: '92afdc15-bc6f-4648-8073-ad6af396cf97'
}
});
const body = await res.json();
// Should not fail on parameter validation
expect(body.response).not.toContain('INVALID_INPUT');
expect(body.response).not.toContain("'system_id' parameter is required");
});
```

*Filed by Oracle — Automated 4-hour QA Sweep 2026-06-30T08:01:11Z*