diagnostics: add comprehensive python process logging in FreeAIService

fix(scoping): inject and use IServiceScopeFactory for background tasks

DIAG: Add /diag/testdbwrite endpoint

LOG: Add trace logging to update processing and image generation flows

FIX: Log webhook set event using ILogger and set dropPendingUpdates: true

FIX: Resolve BeginScope nullability warning in build

DIAG: Print masked token in /diag endpoint

DIAG: Add LastErrorDate to /diag endpoint

DIAG: Add InMemoryLogger and /diag/logs endpoint for C# event visibility

DIAG: Add /diag/db endpoint for real-time database state inspection

REFACTOR: Clean up dead code, placeholders, redundant replicate service, and resolve background thread DI scoping issues

FIX: Call ApplyPythonEnvironmentAsync to inject KAGGLE_GPU_URL environment variable in GenerateImageInternalAsync

FIX: Move photo upload to background task so webhook responds immediately

ADD: /diag endpoint to test Telegram API connectivity

FIX: 300s HTTP timeout for Telegram bot client + retry downloads + no HTTPS redirect

FIX: Remove HTTPS redirect + add retry for photo downloads (3 attempts with backoff)

AUTO-WEBHOOK: Register Telegram webhook on startup. Bot works immediately after every rebuild.

FIX: Read temp files directly instead of MongoDB round-trip. Images now actually load in Telegram.

FIX: Always send photos as byte streams (never FromUri). Fixes MongoDB storage images not loading in Telegram.

UI SIMPLIFY: Two buttons only - Generate + Edit. Clean conversational flow.

GPU auto-registration: dynamic URL resolution from MongoDB

Clear all hardcoded secrets - read from HF Space env vars instead

Deploy app without exposed API tokens