@W-23195592 surface custom step types in cartridge view

[charithaT07]

Summary

Brief description of what this PR does.

Surfaces Custom Step Types as a third category in the Cartridges explorer and adds Workspace Jobs discovery from jobs.xml, with filter UX polish for the Jobs view.

What changed

• Custom Step Types tree — each cartridge now shows a "Step Types" group populated from steptypes.json. Click a step type to open its module .js; right-click → "Show Step Type Definition" jumps to the @type-id line in the JSON.
  Cross-cartridge module resolution supported.
• Workspace Jobs section — Jobs tree now shows a "Workspace" section alongside run history, scanning **/jobs.xml in the workspace. A file-system watcher keeps it in sync. When the server reports a job as not runnable, the user is
  prompted to auto-deploy the definition from the workspace.
• Filter UX — filter icon swaps between outlined/filled based on active-filter state. "Clear All Filters" now resets both status and advanced fields in one action. Active filter summary shown in the tree view message bar.

Testing

• Unit tests added for collectStepTypeEntries (canonical, legacy flat-array, malformed JSON, missing fields) and resolveStepTypeModule (with/without .js, cross-cartridge, unresolvable ref).
• jobs-menu.test.ts updated to assert new commands, filter icon swap, and workspace-job context menu entries.
• Manually verified in Extension Development Host: step types appear under cartridges, click/right-click navigation works, filter icon toggles correctly.

Dependencies

• No net-new third-party dependencies were added
• If net-new third-party dependencies were added, rationale/discussion is included and 3pl-approved is set by a maintainer

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• Tests pass (pnpm test)
• Code is formatted (pnpm run format)