Add tests for legacy momentum signal wrapper

[OnePunchMonk]

This PR adds test coverage for the backward-compatible wrapper create_momentum_signals in src/strategies/momentum.py. This function previously had 0% test coverage.

The new test file tests/test_momentum_legacy.py covers the following cases.

• Passing a Series as input.
• Passing a DataFrame as input.
• Entries and exits are boolean and mutually exclusive.
• Custom fast and slow window parameters produce different signals.
• A flat price series produces no signals.

The README test count badge is bumped from 191 to 196 to match the new total.

Ran the full suite locally with pytest tests/ -q. All 196 tests pass.

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Generated by Claude Code

[OnePunchMonk]

CI is currently red on the Test Suite jobs (Python 3.10, 3.11, 3.12). All three fail at the same ruff check src/ tests/ step, with two findings.

1. tests/test_momentum_legacy.py:5:8 F401, pytest imported but unused. This is in the file this PR adds, so it is this PR's issue.
2. tests/test_tools.py:6:1 I001, import block un-sorted. This file is untouched by this PR (confirmed with git diff origin/main HEAD -- tests/test_tools.py, which is empty) and reproduces the same way against origin/main alone, so it is a pre-existing issue on main, not something this PR introduced.

I'm holding off on pushing a fix for the unused-import lint failure. My task instructions for this PR explicitly said not to push new commits or amend the existing one unless I stop and report back first, so I'm flagging this here rather than fixing it myself. The one-line fix is to drop the unused import pytest from tests/test_momentum_legacy.py.

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Generated by Claude Code

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Generated by Claude Code