feat: reworked UI and made UI available in Linux version

[hanneshapke]

Description

Linked Issue

Closes #

Type of Change

• Bug fix
• New feature
• Refactor / code quality
• Documentation update
• CI / build change

Testing Done

Unit tests (Go):

make test-go

Unit tests (Python):

make test

Linting & type checks:

make lint
make typecheck

Manual testing (if applicable):

• Describe the scenario tested (e.g. PII type detected, proxy request flow, Chrome extension behavior)
• Include before/after behavior if fixing a bug
• Note any edge cases verified (e.g. nested PII in JSON payloads, restoration accuracy)

Checklist

• make test-go and make test pass locally
• make lint reports no new errors
• New PII detection changes are covered by unit tests in tests/
• Go proxy changes include test coverage in src/ or model/
• Documentation updated if behavior or configuration changed
• No sensitive data or credentials included

[github-actions]

Warning

This PR touches 3+ distinct areas of the codebase.

Consider splitting into smaller, focused PRs — each covering a single semantic type.
This makes reviews easier and keeps the git history clean.

Categories found:

docs:

• docs/03-building-deployment.md

code:

• chrome-extension/background.js
• src/backend/config/config.go
• src/backend/embeds.go
• src/backend/embeds_linux.go
• src/backend/main.go
• src/backend/metrics/metrics.go
• src/backend/pii/database.go
• src/backend/proxy/handler.go
• src/backend/proxy/transparent.go
• src/backend/server/dashboard.go
• src/backend/server/server.go
• src/frontend/assets/kiji-dark.svg
• src/frontend/config/webpack.config.js
• src/frontend/index.js
• src/frontend/src/components/AppShell.tsx
• src/frontend/src/components/ErrorBoundary.tsx
• src/frontend/src/components/about/AboutView.tsx
• src/frontend/src/components/activity/ActivityView.tsx
• src/frontend/src/components/dashboard/DashboardView.tsx
• src/frontend/src/components/dashboard/Sidebar.tsx
• src/frontend/src/components/mappings/MappingsView.tsx
• src/frontend/src/components/modals/AboutModal.tsx
• src/frontend/src/components/modals/AdvancedSettingsModal.tsx
• src/frontend/src/components/modals/CACertSetupModal.tsx
• src/frontend/src/components/modals/LoggingModal.tsx
• src/frontend/src/components/modals/MappingsModal.tsx
• src/frontend/src/components/modals/MisclassificationModal.tsx
• src/frontend/src/components/modals/PIISettingsModal.tsx
• src/frontend/src/components/modals/SettingsModal.tsx
• src/frontend/src/components/modals/WelcomeModal.tsx
• src/frontend/src/components/onboarding/WelcomeModal.tsx
• src/frontend/src/components/privacy-proxy-ui.tsx
• src/frontend/src/components/settings/AdvancedSection.tsx
• src/frontend/src/components/settings/CertificatesSection.tsx
• src/frontend/src/components/settings/PIISection.tsx
• src/frontend/src/components/settings/ProvidersSection.tsx
• src/frontend/src/components/settings/SettingsView.tsx
• src/frontend/src/electron/electron-main.js
• src/frontend/src/electron/electron-preload.js
• src/frontend/src/electron/electron.d.ts
• src/frontend/src/electron/ipc-handlers.js
• src/frontend/src/hooks/useDashboardData.ts
• src/frontend/src/hooks/useElectronSettings.ts
• src/frontend/src/hooks/useLogs.ts
• src/frontend/src/hooks/useMappings.ts
• src/frontend/src/hooks/useProxySubmit.ts
• src/frontend/src/hooks/useServerHealth.ts
• src/frontend/src/styles/styles.css
• src/frontend/src/tour/TourProvider.tsx
• src/frontend/src/tour/shepherd-theme.css
• src/frontend/src/tour/tourOptions.ts
• src/frontend/src/tour/tourSteps.ts
• src/frontend/src/tour/useTour.ts
• src/frontend/src/types/dashboard.ts

chore:

• Makefile
• package-lock.json
• src/frontend/package.json
• src/scripts/build_linux.sh
• src/scripts/verify_linux_build.sh

ci:

• .github/workflows/release.yml

other:

• env.example
• packaging/debian/control
• packaging/debian/kiji-privacy-proxy.service
• uv.lock

test:

• src/backend/metrics/metrics_test.go
• src/backend/pii/database_test.go
• src/backend/server/dashboard_test.go
• src/backend/server/server_basic_auth_test.go