feat(THI-54): modernize settings page

[tdody]

Summary

Rebuilds SettingsPage.tsx around the THI-45/46 design system and adds the Appearance + VT tax defaults sections from the ticket.

Header

Caps "Workspace" + serif 44px "Settings" + ink-3 subtitle explaining what persists where.

Appearance (live — applies immediately)

• Theme: <Segmented> Light / Dark wired to existing ThemeContext
• Accent swatches: 5 presets (Teal default / Forest / Amber / Rose / Violet). Selecting a swatch sets --accent on :root to the light-or-dark token value and persists to localStorage["settings.accent"]. Re-applies when the theme flips so dark-mode variants are used.
• Density: <Segmented> Comfortable / Compact — sets document.documentElement.dataset.density and persists. Ready for density-aware CSS; no visual change yet.
• Properties view: <Segmented> Cards / Rows — persists the default dashboard view to localStorage["settings.propertiesView"] for a follow-up that reads it in Dashboard.

Seasonal defaults (backend-persisted)

Three <SliderField> (peak months / peak occupancy / off-peak occupancy) + <SeasonalBars> preview keyed on the current values, with the same accent-vs-ink-3 legend pattern used in the Revenue & Expenses tab.

Vermont tax defaults (new, localStorage-persisted)

4 fields: VT Rooms Tax %, STR Surcharge %, Local Option Tax %, STR Registration Fee. Stored under localStorage["settings.vtTax"]. Wiring them into the new-property flow is a separate follow-up.

Lender packet branding (preserved)

Company name via <Field> + file upload for the logo; file input restyled with caps buttons and border-rule-strong tokens.

Footer

Save changes / Reset buttons. Save writes seasonal + company name to the backend and vtTax to localStorage. Reset reverts the form to the last loaded initial values. Both are disabled when the form is clean.

Test plan

• npm run lint — clean
• npm run build — passes, CSS 46.90 kB, 118 modules
• Dev run: swap theme — Dark/Light segmented matches the app-wide theme immediately
• Select a non-teal accent — --accent updates on the fly; reload persists the choice; flipping theme recomputes the accent for that mode
• Change density / properties view — persists to localStorage
• Drag seasonal sliders — SeasonalBars preview redraws with correct peak/off-peak coloring
• Edit VT tax fields, click Save — reload the page, values come back
• Upload a logo — appears in the preview area; persists across reloads
• Click Reset on a dirty form — reverts to the loaded initial values

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