Delphi 0.4.0: shared skills move from plugins to workspace-inherit/; setup.sh warns about uninstalled plugins

[bracyw]

Shared skills now reach workspaces through workspace-inherit/ (#52) instead of plugins. Nothing has to be installed, which is what broke argos-dev. The plugin plumbing stays in place for later, with no sets for now.

Skills	Were in	Now in
commit, open-pr, update-pr, address-pr-comments, create-ticket	app plugin	application-software/workspace-inherit/
implement, pr-conventions, ticket-conventions, verify-graph	argos plugin	argos/workspace-inherit/
run-local, verify-telemetry	copies in argos-dev, experimental and workspace-defaults/	argos/workspace-inherit/
pr-conventions, ticket-conventions	nero plugin	nero/workspace-inherit/
workflow, review, to-tickets	experimental workspaces	unchanged (the trial)

• No plugin sets are left. The three plugin.json files are gone. ci/plugins.sh, the marketplace, plugins:, application-software/plugins/scope and settings generation all stay. Regenerating gives an empty marketplace, plugins: lists with no sets, and settings.json without enabledPlugins; the DELPHI_ROOT hook is unchanged.
• Delphi 0.4.0: setup.sh warns about enabled plugin sets that aren't installed here, using .delphi/plugins.sh. It stays quiet until a set exists. The CLAUDE.md line about missing plugins was dropped, since nothing is enabled.
• Doc updates:
  • design.md, Argos's AUTHORING.md and README now say shared skills go in workspace-inherit/. A workspace keeps its own copy of one with opt-out:. Plugins are for opt-in sets or harness features beyond files.
  • CLAUDE.md files no longer point at the app or argos plugin.
  • open-pr and create-ticket load the project's conventions skill from workspace-inherit/.
• tests/e2e.sh now builds its own app and argos fixture sets, so the plugin checks don't depend on real sets.

Tests:

• tests/e2e.sh passes all 108 checks, and ci/check.sh passes.
• Dry-run sync on a local mirror with this branch as main:
  • Every ws/* branch refreshed and got its inherited skills. Nero got its own conventions.
  • No enabledPlugins are left, and scripts keep their executable bits.
  • A second sync changed nothing, and nothing was proposed.
• On the real argos-dev clone, plugins.sh printed nothing.