Fix bugs and refactor: AuthContext, ProtectedRoute, DetectorDetail endpoint, settings hardening

[Copilot]

Code review of the Django + React codebase identified several bugs and structural issues that would compound as the project grows. This PR addresses the most impactful ones.

Backend Bugs

• False exception logging: logger.exception("Error creating organization") was called in the success path of Organizations view — fixed to logger.info
• Silent 200 on invalid data: MeasurementsPost had no return when serializer.is_valid() failed, returning None with HTTP 200 — fixed to return HTTP 400 with errors
• Typo: "Detektor not found." → "Detector not found."

Backend Architecture

• Deduplicated check_org_admin_permission: was copy-pasted in both detectors.py and organizations.py — extracted to api/permissions.py
• Added GET /detector/<id>/ endpoint: frontend was fetching all detectors and doing client-side .find() by ID — inefficient and wrong at scale
• Settings hardening: DEBUG = True hardcoded; ALLOWED_HOSTS included "*" — both now read from env vars with safe defaults

Frontend Bug

• Stray literal text in JSX (LogbookEntryPage.tsx line 187): <div className="panel">theme.colors.danger, padding: theme.spacing['3xl'] was rendered as visible text

Frontend Architecture

Eliminated prop-drilling — apiBase, isAuthed, getAuthHeader were passed individually to every page component. Replaced with AuthContext:

// Before: every route passed 3 auth props
<LogbooksPage apiBase={API_BASE} isAuthed={isAuthed} getAuthHeader={getAuthHeader} />

// After: pages consume context directly
export const LogbooksPage = () => {
  const { API_BASE, getAuthHeader } = useAuthContext()
  // ...
}

• ProtectedRoute component: replaced duplicated if (!isAuthed) return <LoginRequired /> in every page with a single wrapper
• isLoading guard in App.tsx: prevents flash of unauthenticated content while token is read from localStorage
• Memoized getAuthHeader with useCallback([token]) so it's stable in useEffect deps
• Shared Detector / DetectorType / DetectorManufacturer types in types.ts: same interface Detector was defined separately in 3+ files
• package.json name typo: dosportal-rect → dosportal-react

Original prompt

Jsi senioeni fullstack vývojář se zaměřením na react, Django.
Podivej se na tento projekt. Je ve vývoji. Mělo by vše být nastavené tak, aby se zpětně nic nemuselo prekopavat od základů. Aktuálně se mimo jiné migrují django views na react.
Vidíš nějaké nedostatky? ať už jde o strukturu, best practices, nebo něco co by se prostě mělo dělat lépe aby se projekt dále dobře vyvíjel.

Záměr se především na strukturu a kod frontend a django rest api, a lehce muzes i na testy.

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[cisar2218]

This agent run was triggered by mistake. Initial prompt was meant to be done to discuss how development direction in this project could be improved.

Most of findings were addressed outside this PR.