feat: Initialize Zastava Webhook service with TLS and Authority authentication

- Added Program.cs to set up the web application with Serilog for logging, health check endpoints, and a placeholder admission endpoint.
- Configured Kestrel server to use TLS 1.3 and handle client certificates appropriately.
- Created StellaOps.Zastava.Webhook.csproj with necessary dependencies including Serilog and Polly.
- Documented tasks in TASKS.md for the Zastava Webhook project, outlining current work and exit criteria for each task.

src/StellaOps.Concelier.Connector.Distro.RedHat/TASKS.md

@@ -13,4 +13,4 @@
 |Express unaffected/investigation statuses without overloading range fields|BE-Conn-RH|Models|**DONE** – Introduced AffectedPackageStatus collection and updated mapper/tests.|
 |Reference dedupe & ordering in mapper|BE-Conn-RH|Models|DONE – mapper consolidates by URL, merges metadata, deterministic ordering validated in tests.|
 |Hydra summary fetch through SourceFetchService|BE-Conn-RH|Source.Common|DONE – summary pages now fetched via SourceFetchService with cache + conditional headers.|
-|Fixture validation sweep|QA|Testing|**DOING (2025-10-10)** – Regenerate RHSA fixtures once mapper fixes land, review snapshot diffs, and update docs; blocked by outstanding range provenance patches.| 
+|Fixture validation sweep|QA|None|**DOING (2025-10-19)** – Prereqs confirmed none; continuing RHSA fixture regeneration and diff review alongside mapper provenance updates.|