Make memory and context views mobile-friendly (#813)

* Changes from fix/memory-and-context-mobile-friendly

* fix: Improve file extension detection and add path traversal protection

* refactor: Extract file extension utilities and add path traversal guards

Code review improvements:
- Extract isMarkdownFilename and isImageFilename to shared image-utils.ts
- Remove duplicated code from context-view.tsx and memory-view.tsx
- Add path traversal guard for context fixture utilities (matching memory)
- Add 7 new tests for context fixture path traversal protection
- Total 61 tests pass

Addresses code review feedback from PR #813

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* test: Add e2e tests for profiles crud and board background persistence

* Update apps/ui/playwright.config.ts

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* fix: Add robust test navigation handling and file filtering

* fix: Format NODE_OPTIONS configuration on single line

* test: Update profiles and board background persistence tests

* test: Replace iPhone 13 Pro with Pixel 5 for mobile test consistency

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

test/opus-thinking-level-none-83449-2bgz7j1/test-project-1772086066067/package.json

@@ -0,0 +1,4 @@
+{
+  "name": "test-project-1772086066067",
+  "version": "1.0.0"
+}