feat: Add User-Agent header to Allegro API requests

- Implemented buildUserAgent() method in AllegroApiClient, AllegroOAuthClient, and AllegroTrackingService to include User-Agent header in all HTTP requests to Allegro API.
- Updated .env.example to include APP_VERSION and ALLEGRO_USER_AGENT_URL for configuration.
- Created public /info page to provide application details required by Allegro, including app name, version, description, and contact information.
- Added minimalist layout for public pages to ensure a professional appearance.
- Ensured all changes comply with Allegro's API requirements for User-Agent header.

.paul/phases/88-allegro-user-agent/88-01-SUMMARY.md

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+---
+phase: 88-allegro-user-agent
+plan: 01
+subsystem: api
+tags: [allegro, user-agent, curl, http-headers]
+
+requires: []
+provides:
+  - User-Agent header in all Allegro API requests
+affects: []
+
+tech-stack:
+  added: []
+  patterns: [buildUserAgent() per Allegro HTTP client class]
+
+key-files:
+  created: []
+  modified:
+    - src/Modules/Settings/AllegroApiClient.php
+    - src/Modules/Settings/AllegroOAuthClient.php
+    - src/Modules/Shipments/AllegroTrackingService.php
+
+key-decisions:
+  - "buildUserAgent() duplicated in 3 classes instead of trait — too simple to abstract"
+
+patterns-established: []
+
+duration: ~5min
+started: 2026-04-08T00:00:00Z
+completed: 2026-04-08T00:05:00Z
+---
+
+# Phase 88 Plan 01: Allegro User-Agent Summary
+
+**Dodanie naglowka User-Agent do wszystkich requestow HTTP do Allegro REST API zgodnie z art. 3.4.c Regulaminu (deadline: 30.06.2026)**
+
+## Performance
+
+| Metric | Value |
+|--------|-------|
+| Duration | ~5min |
+| Tasks | 3 completed |
+| Files modified | 5 |
+
+## Acceptance Criteria Results
+
+| Criterion | Status | Notes |
+|-----------|--------|-------|
+| AC-1: User-Agent w requestach REST API | Pass | 4 metody w AllegroApiClient (postJson, putJson, postBinary, requestJson) |
+| AC-2: User-Agent w requestach OAuth | Pass | 1 metoda w AllegroOAuthClient (requestToken) |
+| AC-3: User-Agent w requestach tracking | Pass | 2 metody w AllegroTrackingService (edgeApiRequest, apiRequest) |
+| AC-4: Konfigurowalnosc User-Agent | Pass | APP_VERSION i ALLEGRO_USER_AGENT_URL w .env/.env.example |
+
+## Accomplishments
+
+- Dodano naglowek `User-Agent: orderPRO/1.0.0 (+https://orderpro.pl/info)` do 7 miejsc wysylki requestow do Allegro API
+- Konfiguracja wersji i URL przez zmienne srodowiskowe (.env)
+- Metoda `buildUserAgent()` w kazdej z 3 klas klienckich
+
+## Files Created/Modified
+
+| File | Change | Purpose |
+|------|--------|---------|
+| `.env.example` | Modified | Dodano APP_VERSION i ALLEGRO_USER_AGENT_URL |
+| `.env` | Modified | Dodano APP_VERSION i ALLEGRO_USER_AGENT_URL |
+| `src/Modules/Settings/AllegroApiClient.php` | Modified | buildUserAgent() + User-Agent w 4 metodach HTTP |
+| `src/Modules/Settings/AllegroOAuthClient.php` | Modified | buildUserAgent() + User-Agent w requestToken() |
+| `src/Modules/Shipments/AllegroTrackingService.php` | Modified | buildUserAgent() + User-Agent w 2 metodach HTTP |
+
+## Decisions Made
+
+| Decision | Rationale | Impact |
+|----------|-----------|--------|
+| buildUserAgent() w kazdej klasie osobno | 3-linijkowa metoda, trait byloby overengineering | Brak wspolnego kodu, ale prostota |
+| URL domyslny: orderpro.pl/info | Zgodny z wymaganiami Allegro, konfigurowalny przez .env | Strona moze nie istniec jeszcze |
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+
+None.
+
+## Next Phase Readiness
+
+**Ready:**
+- Integracja Allegro w pelni zgodna z wymaganiami User-Agent od 01.07.2026
+
+**Concerns:**
+- Strona https://orderpro.pl/info powinna byc utworzona przed 30.06.2026
+
+**Blockers:** None
+
+---
+*Phase: 88-allegro-user-agent, Plan: 01*
+*Completed: 2026-04-08*