[G5] Achievements screen and 3-badge profile showcase

Where a user browses what they have unlocked and what is left.

Depends on: [G3] MVP achievement catalogue (artwork + wording), [G4] Profile progression display (privacy rules).

Scope

• A screen listing achievements, grouped by family, showing progress before unlock (e.g. "42 / 100", rendered in the .timecode mono style per DESIGN.md).
• Locked, in-progress, unlocked and secret states. A secret entry occupies a visible slot with hidden content.
• Tiers rendered as a single family, not as N unrelated entries.
• Showcase: 3 pinned achievements on the profile, chosen by the user.
• Same visibility rules as G4 — audiences per domain, nothing at all for a Figurant.
• Data fetching through createApiQuery and the key factory, per the repo's API layer conventions.

Open question for implementation

Naming and shape of the screen (an "achievements card", a grid, a per-domain breakdown) — not settled, decide it here.

Out of scope

Unlock animations and reward feedback (G6).