feat: publish browsable Chinese package purposes

[tifycloud]

Summary

• publish a SHA-bound Chinese-purpose sidecar covering every unique source/package in the current package catalog
• show all packages without requiring search, with pagination, Chinese search, quality labels, and the original upstream description
• fail closed when the purpose catalog, package shards, key coverage, or integrity metadata do not validate
• add deterministic generation, safe root-descriptor updates, documentation, workflow integration, and regression tests

Catalog

• unique packages: 12,271
• exact descriptions: 90
• family-rule descriptions: 7,212
• conservative category descriptions: 4,969
• sidecar SHA-256: a562f8ac63e51caa1881bf536abcb457ab45c27c5d426e46d9510266774b10b0

Verification

• python3 tests/test_package_catalog.py
• python3 tests/test_component_catalog_staging.py (22/22)
• python3 tests/test_package_purpose_zh.py (10/10)
• node tests/test_pages_ui.js
• bash tests/test_pages_policy.sh
• bash tests/test_static.sh
• independent read-only review: APPROVE; no P0/P1/P2 or release blockers