fix: Hard Rule 0 should verify MCP environment affinity before use

## Problem

When the user specifies a target org URL (e.g. `Dataverse organization: https://orga14dc4b7.crm.dynamics.com`) and an MCP server is registered for a DIFFERENT environment, Hard Rule 0 says "use MCP directly, skip setup." The agent queries the wrong MCP, gets empty/incorrect results, then has to fall back to CLI -- wasting 10-20s on a dead-end path.

Observed in Codex evals: MCP was registered for `aurorabapenv9880b` but the eval prompt targeted `orga14dc4b7`. The agent used MCP (empty results), then spent time diagnosing before finding the CLI profile for the correct org.

## Root cause

Hard Rule 0 in dv-overview currently says:

> "If any Dataverse MCP tool is found, use it directly -- skip the init check and all setup."

This assumes a single-environment session. Multi-environment scenarios (evals, consultants, dev/test switching) break this assumption.

## Proposed fix

Add environment affinity verification to Hard Rule 0:

1. If the user prompt specifies an org URL, extract the org identifier
2. Check whether the discovered MCP tool name contains a matching org ID (tools are named like `mcp__dataverse___read_query`)
3. If MCP matches the requested org -- use it directly (current behavior)
4. If MCP does NOT match -- skip MCP, fall through to CLI/SDK for the requested org

This keeps the fast path for single-environment sessions while preventing wrong-org queries in multi-environment scenarios.

## Impact

Every eval prompt in the compete suite includes an explicit org URL. When the Codex sandbox has an MCP from a previous session or a different org, every prompt wastes 10-20s on a wrong-MCP dead end before falling back.

## Acceptance criteria

- Agent verifies MCP environment affinity before using it when the prompt contains an explicit org URL
- Single-environment sessions (no explicit URL in prompt) are unaffected
- Static checks pass

Start at Hard Rule 0 in dv-overview and review how discovered MCP tools are selected when an org URL is present. Verify the environment-affinity behavior for matching and non-matching MCP tools, confirm prompts without an explicit URL remain unaffected, and run the repository's static checks.

Written by the indexing model from the issue text.