Prepare CLI 0.5.3 with congestion-aware rendering

[konojunya]

Background

Stack Engine 0.9.0 and Theme 0.7.0 improve dense connector routing and replace the built-in cache cylinder with the approved rounded card. The native CLI must use the same released engine and theme as the Web renderer.

Implementation Approach

• Bump Stack CLI to 0.5.3 while preserving 0.5.2 as the currently activated distribution version until release verification completes.
• Pin registry-only stack-engine =0.9.0 and stack-theme =0.7.0, update the lockfile and dependency notices, and regenerate the versioned manual page.
• Add release notes describing the intentional SVG geometry changes and unchanged command/configuration contracts.

Testing Approach

• Rust 1.85 all-feature unit, integration, formatter, template, and render conformance tests.
• Clippy with warnings denied and exact coverage gates (92.01% lines, 96.58% functions, 92.12% regions).
• All 82 JavaScript release/distribution contract tests and five Python archive tests.
• Registry-only Cargo publish dry run, standalone SVG validation, generated CLI assets, version, and doctor smoke checks.

Review Perspectives / Points of Concern

• SVG geometry and deterministic bytes intentionally change; CLI commands, configuration, JSON contracts, and the Rust 1.85 minimum do not.
• The source version advances to 0.5.3, but public channel activation remains pinned to 0.5.2 until immutable release artifacts and clean-install checks succeed.
• No self-update behavior is added; Homebrew, Cargo, Aqua, and verified direct installation retain ownership of upgrades.