Refine social preview claims

[SFlann]

Outcome

Refine the repository social preview so its claims are precise and its decoder illustration is clear at link-preview size.

Design

• describe the package as a typed Python SDK rather than using the more ambiguous “Typed API” badge
• narrow the Stim claim to “Stim-checked algebra,” matching its development-only conformance tests
• show all 12 memory-experiment rounds and four decoder windows
• move the final-frame label below the decoder bars so it no longer overlaps the visualization

The package does not gain a Stim runtime dependency; Stim remains an independent development-time oracle for the documented algebra checks.

Verification

• Formatting and lint pass
• Tests pass: 364 tests
• Required 100% statement and branch coverage retained
• Regenerated PNG is 1280×640 and under GitHub’s size limit
• Rendered image inspected at original resolution

Release impact

No public API, dependency, compatibility, or distribution changes.