feat: add hosted mode support for Spoolman shell embedding

[akira69]

Summary

Adds a focused hosted-mode path so spoolman-filament-swatch can run cleanly inside the Spoolman Applications Framework as a same-origin embedded app while preserving standalone mode.

This branch is intended to pair with the hosted-shell work happening in akira69/Spoolman_Labels on feat/hosted-applications-framework-workspace.

What Changed

• add hosted-mode route defaults so embedded launches land on /app/swatch
• add hosted-mode title/branding support so the app reads as Filament Swatch when embedded
• strip standalone-only manifest/search/canonical links from hosted builds
• accept host-provided theme state and mirror the parent shell instead of exposing a separate theme selector
• treat hosted config as authoritative for backend/API access
• allow hosted mode to load Spoolman data correctly from root or subpath deployments
• fix stale spoolmanUrl on first render: useSpoolmanUrl is a module-level singleton evaluated before bootstrap() resolves — rehydrateFromHostedConfig() corrects it after the async hosted config is fetched, before any connection check fires
• deduplicate HostedConfig/HostedWindow types: export from useHostedMode.ts; main.ts imports rather than re-declaring them

Hosted Runtime Behavior

When launched by a host shell, the app now:

• reads a small hosted config payload from the parent runtime
• uses host-provided Spoolman base-path context
• follows the parent dark/light mode
• hides the standalone theme switch
• skips standalone landing-path assumptions
• preserves standalone behavior when no hosted config is present

Verification

Verified locally against a same-origin Spoolman host shell on 2026-03-23:

• hosted app launched under /app-host/spoolman-filament-swatch/
• embedded route defaulted into the swatch UI
• embedded title rendered as Filament Swatch
• app-local theme selector was removed in hosted mode
• parent Spoolman dark mode propagated into the hosted app
• hosted app loaded seeded filament/spool data through the parent Spoolman instance

Notes

• This PR intentionally keeps the changes narrow and host-oriented.
• It does not vendor Spoolman-specific code into the app beyond the small hosted contract path.
• The search-bar visibility fix on narrow widths is a separate concern tracked in PR fix: keep search visible on narrow widths #27.
• A remaining follow-up outside this repo is cleaning up the parent shell's nested-route service worker 404 in the browser console.