Add passCome68 strategy, helper, tests, and README example

[tphummel]

Motivation

• Provide a compact composite betting strategy that places a minimum pass-line with max odds, a minimum come-line with max odds, and only places 6/8 when those numbers are not already covered by the pass point or come points.
• Avoid duplicate/conflating place bets that conflict with existing pass or come points.
• Make the pending-come behavior explicit so only a single pending come bet is created when intended.
• Document how to run the new strategy from the CLI in the README with an example.

Description

• Added a helper placeSixEightUnlessPassOrCome which removes newly-created place 6/8 bets when the pass point or existing come points already cover them.
• Introduced the composite strategy passCome68 that composes minPassLineMaxOdds, minComeLineMaxOdds, and placeSixEightUnlessPassOrCome, and exported it.
• Refactored minComeLineMaxOdds to use pendingCount and pointCount and only create a pending come bet when pendingCount === 0 && pointCount < maxComeBets, and added/renamed related wrapper functions.
• Added unit tests in betting.test.js validating minComeLineMaxOdds behavior, passCome68 behavior (skipping place bets covered by pass or come), and updated exported function names; and added a README example CLI invocation of passCome68.

Testing

• Ran the test suite with npm test during the earlier rollout and the TAP output shows all tests passing.
• minComeLineMaxOdds unit tests were added and passed, including a test ensuring only one pending come bet is created.
• New passCome68 unit tests were added and passed, covering pass odds, come pending bet, and skipped place bets behavior.
• The README change is documentation-only and does not require additional test changes.

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Codex Task