Add project-wide instruction files for Fuchs migration

Added detailed instruction files for configuration, controller structure, C# standards, OCORE library usage, ImageSharp licensing, and testing. These documents define rules for settings, DI, file layout, package management, and test practices to ensure consistency and compliance during the .NET 10 migration.

.github/instructions/imagesharp.instructions.md

@@ -0,0 +1,29 @@
+---
+applyTo: "Fuchs/**,OCORE/**,OCORE_web/**,OCORE_web_pdf/**"
+---
+
+# SixLabors ImageSharp Instructions
+
+## Licensing (v4.0.0+)
+- `SixLabors.ImageSharp` v4.0.0+ requires a license; builds fail validation without one.
+- **Do not downgrade ImageSharp** to avoid the license requirement.
+- Each project that references ImageSharp needs its own discoverable `sixlabors.lic` file in the project root.
+- Tracked license files exist for `OCORE`, `OCORE_web`, and `Fuchs`. Use `OCORE_web/OCORE_web/sixlabors.lic` as the canonical Community-license template.
+- Do **not** create untracked local duplicates of `sixlabors.lic` — an untracked copy blocks `git pull` when upstream adds a tracked one.
+
+## License File Format
+A single-line Community license payload:
+```
+Id=...;Kind=Community;ExpiryDateUtc=...;Key=...
+```
+
+## v4.0.0 API / Namespace Changes
+When updating or fixing ImageSharp-related code, account for these breaking moves:
+
+| Removed / old | Use instead |
+|---------------|-------------|
+| `using SixLabors.ImageSharp.ColorSpaces;` | Removed — delete if unused |
+| `using SixLabors.ImageSharp.Web.DependencyInjection;` | `using SixLabors.ImageSharp.Web;` |
+
+- `AddImageSharp(...)` / `UseImageSharp()` resolve from `SixLabors.ImageSharp.Web` (plus `.Commands` and `.Processors` for related types).
+- After any ImageSharp version change, rebuild and confirm middleware bootstrap in `OCORE_web/OCORE_web/web/OCORE_appbuilder.cs` still compiles.