Feedback iteration: DialogShell, page consistency, popup standardisation

- Add DialogShell atom — shared dialog container (header, scrollable body, footer)
- Refactor FilterPanel to use DialogShell (Popover → centered Dialog)
- Refactor ArrangementDialog to use DialogShell
- Remove PreviewStep + AuthGateStep pages (consolidated into ArrangementDialog, D-E)
- IntroStep: static subheading, top-left aligned toggle button content
- ProvidersStep: h4 heading "Find a funeral director", location search with pin icon,
  filter moved below search right-aligned, map fill fix, hover scrollbar
- VenueStep: same consistency fixes (h4 heading, filter layout, location icon, map fix)
- PackagesStep: grouped packages ("Matching your preferences" / "Other packages from
  [Provider]"), removed budget filter + Most Popular badge, clickable provider card,
  onArrange replaces onContinue, h4 heading
- WizardLayout: list-map left panel gets thin scrollbar visible on hover

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/memory/component-registry.md

@@ -32,6 +32,7 @@ duplicates) and MUST update it after completing one.
 | Slider | planned | single, range × desktop, mobile | | Price range filter. Wraps MUI Slider. Deferred until search/filtering molecules. |
 | Link | done | underline: hover/always/none × any MUI colour | color.text.brand (copper brand.600, 4.8:1), color.interactive.active | Navigation text link. Wraps MUI Link. Copper default, underline on hover, focus ring. |
 | Collapse | done | in/out × unmountOnExit | (none — uses MUI defaults) | Progressive disclosure wrapper. Thin MUI Collapse wrapper with unmountOnExit default. Slide-down animation for wizard field reveal. |
+| DialogShell | done | open/closed × with/without back button × with/without footer | (theme defaults — borderRadius, palette) | Standard dialog container. Header (title + optional back + close), divider, scrollable body, optional footer. Used by FilterPanel and ArrangementDialog. |
 | ToggleButtonGroup | done | exclusive single-select × small, medium, large × error × fullWidth + descriptions | color.neutral.100-200, color.brand.50/100, color.interactive.focus, color.feedback.error | Button-select for binary/small-set choices. Fieldset/legend a11y, external label, helper/error text. Brand styling on selected. |
 
 ## Molecules
@@ -76,8 +77,8 @@ duplicates) and MUST update it after completing one.
 | IntroStep | done | WizardLayout (centered-form) + ToggleButtonGroup × 2 + Collapse + Typography + Button + Divider | Wizard step 1 — entry point. forWhom (Myself/Someone else) + hasPassedAway (Yes/No) with progressive disclosure. Auto-sets hasPassedAway="no" for "Myself". `<form>` wrapper, aria-live subheading, grief-sensitive copy. Pure presentation. Audit: 18/20 → 20/20 after fixes. |
 | ProvidersStep | done | WizardLayout (list-map) + ProviderCard + SearchBar + Chip + Typography + Button | Wizard step 2 — provider selection. List-map split: provider cards w/ radiogroup + search + filter chips (left), map slot (right). aria-live results count, back link. ProviderCard extended with HTML/ARIA passthrough. Audit: 18/20. |
 | PackagesStep | done | WizardLayout (list-detail) + ProviderCardCompact + ServiceOption + PackageDetail + Badge + TextField + Typography + Button | Wizard step 3 — package selection. List-detail split: compact provider + budget filter + package list w/ radiogroup (left), PackageDetail breakdown (right). "Most Popular" badge. Mobile Continue button. |
-| PreviewStep | done | WizardLayout (list-detail) + ProviderCardCompact + PackageDetail + Typography + Button + List + Divider | Wizard step 4 — package review. Informational (no form fields). "What happens next" numbered checklist. Pre-planning shows "Explore other options" tertiary CTA. |
-| AuthGateStep | done | WizardLayout (centered-form) + TextField + MenuItem + Collapse + Button + Divider | Wizard step 5 — auth gate. 3 progressive sub-steps: SSO/email → details → verify. Phone optional when email-only. Benefit framing. Audit: 18/20. |
+| ~~PreviewStep~~ | removed | — | Replaced by ArrangementDialog organism (D-E). Package preview + "what's next" checklist now in the dialog's preview step. |
+| ~~AuthGateStep~~ | removed | — | Replaced by ArrangementDialog organism (D-E). SSO/email auth flow now in the dialog's auth step. |
 | DateTimeStep | done | WizardLayout (centered-form) + TextField + RadioGroup + Autocomplete + Collapse + Divider + Button | Wizard step 6 — details & scheduling. Deceased name + date/time radios + religion Autocomplete. Two fieldset sections. Grief-sensitive labels. Save-and-exit CTA. |
 | VenueStep | done | WizardLayout (centered-form) + VenueCard + AddOnOption + Collapse + Chip + TextField + Divider + Button | Wizard step 7 — venue selection. Consolidated from 3 baseline steps. Card grid with search/filters, inline detail, service toggles (photo, streaming, recording). |
 | CrematoriumStep | done | WizardLayout (centered-form) + Card + RadioGroup + Collapse + TextField + Divider + Button | Wizard step 8 — crematorium. Single confirmation card or multi-card grid. Witness question personalised with deceased name. Special instructions textarea. |