fix: add Technically Unsupported section to SCOPE.md (#1295)

## Summary

**Goal of this PR**
Add an **"In-scope — technically not supported"** section to `SCOPE.md`.

This clarifies hardware/UX limitations (e.g., clock support) and is
intended to reduce recurring feature requests on topics already
discussed.

Based on discussions in #287 and #626.

---

### AI Usage

While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.

Did you use AI tools to help write this code? _**< NO >**_

SCOPE.md

@@ -39,6 +39,14 @@ usability over "swiss-army-knife" functionality.
 * **Complex Annotation:** No typed out notes. These features are better suited for devices with better input
   capabilities and more powerful chips.
 
+### In-scope — Technically Unsupported
+
+*These features align with CrossPoint's goals but are impractical on the current hardware or produce poor UX.*
+
+* **Clock Display:** The ESP32-C3's RTC drifts significantly during deep sleep; making the clock untrustworthy after any sleep cycle. NTP sync could help, but CrossPoint doesn't connect to the internet on every boot.
+
+* **PDF Rendering:** PDFs are fixed-layout documents, so rendering them requires displaying pages as images rather than reflowable text — resulting in constant panning and zooming that makes for a poor reading experience on e-ink.
+
 ## 3. Idea Evaluation
 
 While I appreciate the desire to add new and exciting features to CrossPoint Reader, CrossPoint Reader is designed to be