MCM-54 — Unified Icon System

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As a Frontend Engineer,
I want one icon library, at one consistent version, with a shared and curated set of icons approved for use,
so that an icon looks and behaves the same regardless of which surface renders it, and I'm not choosing between different icon libraries or introducing a new one ad hoc.

Acceptance Criteria

• All three surfaces use the same general-purpose icon library at the same version, rather than each surface pinning its own version independently as today.
• A curated, named set of approved icons is documented (see MCM-55), so an engineer picks from an existing icon before reaching for a new one.
• Where a surface renders a brand or third-party provider logo that the general-purpose icon library doesn't cover, the shared system defines a documented escape hatch for adding it, rather than reintroducing a second general-purpose icon library.
• Icons render consistently in both light and dark appearance, and at the sizes already in common use (inline text-sized icons as well as larger stat/illustration icons).
• Upgrading the shared icon library's version is a single, coordinated change across all three surfaces rather than three independent upgrades that can drift out of sync again.

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Technical Design

Today, two of the three surfaces already use the same general-purpose icon library but at two different major versions, and one of those surfaces also reaches for a second, brand-specific icon library for third-party provider logos alongside its primary one. This story pins one shared version of the primary icon library across all three surfaces and defines a small, explicit escape hatch for brand or provider icons the general-purpose library doesn't include, so a second general-purpose library isn't reached for arbitrarily. The curated icon set ships as part of the same shared package as MCM-52 and MCM-53.

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UI / Frontend Changes

• Icon imports across all three surfaces are standardised on the shared set and version rather than each surface's own import.
• A documented escape hatch remains for brand/provider icons not covered by the general-purpose set.
• No visual change for icons already matching the shared set; icons on the surface(s) running a different version converge to the shared version's rendering.