3.7.0 — Bespoke plugins page, public API docs, sign-in fix

Added

• A public page at /bespoke-plugins describing bespoke plugin work: how a commission goes, the Twilight Struggle plugin as an example, and how to get in touch. shrkbot itself stays free; a bespoke plugin may carry a small fee agreed up front. Linked from the top bar for both signed-out visitors and dashboard users. (#227)
• Public API documentation at badblackshark.github.io/shrkbot, generated from the OpenAPI schema. Covers the base URL, key auth, idempotent upserts and status codes, plus per-field descriptions and response bodies for the Twilight Struggle API, so the machine-readable contract no longer has to be requested by mail. (#226)

Fixed

• Signing in with Discord did nothing in Safari and Chromium browsers: the site's Content Security Policy blocked the form submission once it redirected to Discord, with no visible error. Firefox was unaffected, which made it look like a mobile-only problem. (#225)