Add optionsahoy plugin under Integrations

[AlvisoOculus]

One README entry under Integrations, matching the existing external-link format (same pattern as kaggle-skill).

• optionsahoy: deterministic US equity-compensation tax optimizer for Claude Code. It bundles a hosted MCP server (https://optionsahoy.com/mcp, HTTP, no auth key) plus one planning skill that routes to the right tool and captures required inputs.
• Real use case: incentive stock option (ISO) exercise and alternative minimum tax (AMT) planning, non-qualified stock option (NSO) and restricted stock unit (RSU) decisions, single-stock concentration, protective puts, qualified small business stock (QSBS) checks, and equity funding plans. Federal plus 50-state plus DC tax math, computed deterministically rather than generated.
• No duplicate of anything on the list; MIT licensed; installable today via /plugin marketplace add AlvisoOculus/optionsahoy-claude-plugin then /plugin install optionsahoy@alphalatitude. Tested end to end with claude plugin validate and a live install.