refactor(storybook): remove unused SW header demo stories

Remove nine SW/Header demo pages (property-fields, property-shape-slot,
composition, colorize, dynamic-controls, property-bar, additional-hover,
property-panel, layer-detail-input) and the demo code and Storybook-only
CSS used only by them. SW Stories 19 -> 10, total 338 -> 329.

The package runtime, public API, AI template and the retained Stories
(Overview, Dropdown, Property Panel 4-state comparison, Window Move
Motion and others) are unchanged. Add a current regression script and
mark the older scripts that open the retired IDs as historical evidence.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/sw/tests/storybook-inventory.mjs

@@ -3,6 +3,8 @@ export const retiredStage1Ids = ['responsive', 'text-stroke', 'dynamic-data', 'd
 export const retiredDropdownIds = ['layer-dropdown', 'color-dropdown', 'line-style-dropdown', 'text-dimension-style-dropdown'].map(id => `sw-header--${id}`)
 // 2026-10-19: duplicate property panel demos; the four states live on sw-header--property-panel-compare.
 export const retiredPropertyPanelIds = ['property-panel-variants', 'property-panel-none', 'property-panel-all', 'property-panel-circle', 'property-panel-expanded'].map(id => `sw-header--${id}`)
+// 2026-10-19: unused SW Header demo pages; their features stay in the package and the retained Stories.
+export const retiredUnusedDemoIds = ['property-fields', 'property-shape-slot', 'composition', 'colorize', 'dynamic-controls', 'property-bar', 'additional-hover', 'property-panel', 'layer-detail-input'].map(id => `sw-header--${id}`)
 // Include the old title when reading historical evidence; live hierarchy is asserted separately.
 export const swStoryEntries = index => Object.values(index.entries).filter(entry => entry.type === 'story' && (entry.title === 'SW/Header' || entry.title === 'SW/Header/Dropdown'))
 export const retainedInventory = entries => entries.filter(entry => ![...retiredStage1Ids, ...retiredDropdownIds].includes(entry.id))