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/STATE.md

@@ -5,19 +5,19 @@
 See: .paul/PROJECT.md (updated 2026-04-08)
 
 **Core value:** Sprzedawca moze obslugiwac zamowienia ze wszystkich kanalow sprzedazy i nadawac przesylki bez przelaczania sie miedzy platformami.
-**Current focus:** Milestone v3.0 - Phase 87 complete, ready for next PLAN
+**Current focus:** Milestone v3.0 - Phase 89 complete, ready for next PLAN
 
 ## Current Position
 
 Milestone: v3.0 Mobile Responsive - In progress
-Phase: 87 (Shipment Delete) — Complete
-Plan: 87-01 unified
+Phase: 89 (Allegro Info Page) — Complete
+Plan: 89-01 unified
 Status: Loop complete, ready for next PLAN
-Last activity: 2026-04-08 — Unified .paul/phases/87-shipment-delete/87-01-PLAN.md
+Last activity: 2026-04-08 — Unified .paul/phases/89-allegro-info-page/89-01-PLAN.md
 
 Progress:
 - Milestone: [#########.] ~93%
-- Phase 87: [##########] 100%
+- Phase 89: [##########] 100%
 
 ## Loop Position
 
@@ -30,11 +30,6 @@ PLAN ──▶ APPLY ──▶ UNIFY
 ## Session Continuity
 
 Last session: 2026-04-08
-Stopped at: Plan 87-01 unified
+Stopped at: Plan 89-01 unified
 Next action: Run /paul:plan for the next prioritized phase
-Resume file: .paul/phases/87-shipment-delete/87-01-SUMMARY.md
-
-## Git State
-
-Last commit: 8fa9ca6
-Branch: main
+Resume file: .paul/phases/89-allegro-info-page/89-01-SUMMARY.md