Use rounded cache cards in core themes

[konojunya]

Background

The built-in cache cylinder adds a decorative top ellipse that can visually compete with labels and borders. Database fallbacks already use a cleaner rounded card while keeping their semantic icon.

Implementation Approach

• Render built-in cache fallbacks as 8 px rounded rectangles in the default, light, and dark themes.
• Preserve cache colors, minimum dimensions, and the existing semantic cache icon.
• Keep the cylinder shape available to custom themes.
• Advance the catalog and Rust crate to 0.7.0 with generated Cargo/JavaScript artifacts and release notes.

Testing Approach

• Generated catalog drift and schema validation.
• 24 catalog/provider/SVG tests and TypeScript checks.
• Rust stable and Rust 1.85 tests, Clippy, Rustdoc, and Cargo publish dry-run.
• npm package dry-run and Rust/JavaScript catalog parity.
• Browser-rendered sample review across the built-in themes.

Review Perspectives / Points of Concern

• Confirm the cache silhouette is visually consistent with the approved database card treatment.
• Confirm semantic identity remains clear through the cache icon after removing the decorative cylinder cap.
• Confirm no custom-theme shape capability is removed.