feat(core): theme service refactor (#DS-3003)

[NikGurev]

Summary

Refactors ThemeService (DS-3003) into a signal-based KbqThemeService: a closed mode: 'auto' | 'light' | 'dark' signal resolved against the OS color scheme and a registered themes() set, replacing index/name-based selection with colorScheme-driven resolution. ThemeService is kept as a deprecated facade for backward compatibility.

Notable changes

• added KbqThemeService — signals mode, themes, currentTheme, colorScheme; toggle() flips light/dark; persists via a swappable KBQ_THEME_STORE (KbqThemeLocalStorageStore by default, KbqThemeCookieStore for live SSR)
• added KbqThemeConfig (name, className, required colorScheme) replacing KbqTheme for registered themes, plus KbqDefaultThemes/KbqThemeSelector/KbqThemeNames for the built-in light/dark set
• added kbqThemeProvider(config) / KBQ_THEME_CONFIG for DI-based setup (custom themes, initial mode, storage key)
• kept ThemeService, KbqTheme, current/setTheme()/getTheme() as deprecated shims backed by KbqThemeService
• updated internal consumers (navbar, dev apps) to the new API; refreshed theme.service.spec.ts and core.api.md

What should reviewers focus on

• Whether the deprecated back-compat surface is worth keeping vs. a cleaner break
• mode/colorScheme as the final shape, replacing the earlier selection/autoLight/autoDark draft

[github-actions]

Visit the preview URL for this PR (updated for commit c59aa1e):

https://koobiq-next--prs-1856-jmotwjcq.web.app

_{(expires Sun, 16 Aug 2026 07:12:11 GMT)}

_{🔥 via Firebase Hosting GitHub Action 🌎}

_{Sign: c9e37e518febda70d0317d07e8ceb35ac43c534c}

[Copilot]

Pull request overview

This PR refactors the core ThemeService (DS-3003) into a signal-based KbqThemeService. It introduces a built-in auto mode that follows the OS color scheme via matchMedia, adds out-of-the-box mode persistence through a swappable KBQ_THEME_STORE (default KbqThemeLocalStorageStore), and DI-based configuration via kbqThemeProvider()/KBQ_THEME_CONFIG. Backward compatibility is preserved: ThemeService remains as a deprecated alias, and current, KbqTheme.selected, setTheme()/getTheme() still work. Consumers across the docs app and docs-examples are migrated to the signal API, and the docs navbar's hand-rolled matchMedia/localStorage wiring is removed.

Changes:

• New signal-based KbqThemeService (mode, resolvedMode, currentTheme, themes) with setAuto()/toggle()/setMode(), internal OS-scheme handling, and DI config (kbqThemeProvider, KBQ_THEME_CONFIG, KBQ_THEME_STORE, KbqThemeLocalStorageStore).
• Deprecated back-compat surface kept (ThemeService alias, current, selected, setTheme/getTheme); public API snapshot approved.
• Migrated all consumers (navbar, welcome, docsearch, tokens-overview, theme-toggle, 7 docs-examples) to the signal API; added theme.service.spec.ts and migration docs.

Reviewed changes

Copilot reviewed 20 out of 20 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/components/core/services/theme.service.ts	New KbqThemeService, config/store tokens, deprecated ThemeService alias.
packages/components/core/services/theme.service.spec.ts	New unit tests for auto/mode/custom themes/persistence/SSR/deprecated shims.
tools/public_api_guard/components/core.api.md	Approved public API changes for the new/renamed symbols.
apps/docs/src/app/config.ts	Wires kbqThemeProvider({ storageKey: 'docs_theme' }) (see comment — format mismatch).
apps/docs/src/app/components/navbar/navbar.component.ts / navbar.template.html	Removes hand-rolled matchMedia/storage; drives dropdown off mode()/setMode().
apps/docs/src/app/components/welcome/welcome.component.ts	Uses resolvedMode() computed instead of current observable.
apps/docs/src/app/components/docsearch/docsearch.directive.ts	Uses toObservable(resolvedMode) for the search theme.
apps/docs/src/app/components/design-tokens-viewers/tokens-overview.ts / .spec.ts	Recalculates via effect on resolvedMode(); test mocks matchMedia.
packages/components-dev/theme-toggle.ts	Dev toggle rewired to resolvedMode()/setMode() via effect.
packages/docs-examples/** (7 files)	Switched currentTheme to resolvedMode() computed; dropped unused rxjs imports.
docs/guides/migration.en.md / migration.ru.md	Adds a "13. Theme service review" migration section.

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.