- Update renderHeader and renderCollapsibleHeader in renderer-registry.ts to accept `text: string | TemplateResult`
- Remove duplicated renderCollapsibleHeaderWithPill helper in artifacts-tool-renderer.ts
- Update all artifact renderer calls to use renderHeaderWithPill() inline
- Remove all separate pill rendering below headers
This allows artifact pills to be rendered inline with header text without code duplication.
- Create ArtifactPill component (similar to SkillPill)
- Renders filename as clickable pill with FileCode2 icon
- Clicking pill opens artifacts panel and selects that artifact
- Update ArtifactsToolRenderer to accept artifactsPanel reference
- Pass artifactsPanel from ChatPanel to renderer on initialization
- Display artifact pill below header for all commands
- Pill only clickable when artifactsPanel reference is available