Fix skills install flow and improve bundle export handling

[danieldear]

Summary\n- fix curated skills registry install URLs and surface install status in the Browse tab\n- remove ghost unresolved refs from package helper files in export UI associations\n- export same-stem sibling dependency folders for flat tools\n- reject binary assets clearly for current .a7bundle v1 text-only export path\n- add .a7bundle v2 and artifact versioning design doc\n\n## Verification\n- cargo check -p agent007-sharing -p agent007-web\n- cargo test -p agent007-web package_skill_helper_files_do_not_become_ghost_script_refs -- --nocapture\n- cargo test -p agent007-sharing builder_flat_tool_export_includes_same_stem_dependency_dir -- --nocapture\n- cargo test -p agent007-sharing builder_rejects_binary_tool_assets_with_clear_error -- --nocapture

[Copilot]

Pull request overview

This PR updates curated skill installation and bundle export behavior, with supporting documentation for a future binary-safe .a7bundle format.

Changes:

• Updates the curated skills registry URLs and adds a local registry fallback.
• Adjusts package skill association scanning and bundle export dependency collection.
• Adds tests for package helper association handling, flat tool dependency export, and binary rejection.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
docs/registry.json	Refreshes curated skill entries and raw install URLs.
docs/a7bundle-v2.md	Adds the proposed v2 bundle/archive design.
crates/web/src/api.rs	Adds registry fallback and changes package skill association extraction.
crates/web/frontend/src/views/SkillsView.vue	Shows import/install status in the Browse tab.
crates/sharing/src/lib.rs	Adds text-only asset reading errors and same-stem flat tool dependency export.

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