feat: disasm popup, symbol separation, context menu improvements, RVA fixes

- Add Fadec x86 disassembler with hover popup for FuncPtr/void Pointer nodes
- Separate pointer symbol from address: // prefix, green comment coloring,
  independent hover/click zones (address triggers popup, symbol is passive)
- Fix RVA margin and inline local offset for pointer-expanded vtable children
  using ptrBase field threaded through composition
- Expand multi-select context menu with quick-convert, duplicate, copy address
- Remove Edit Value from hex node context menu
- Fix heatmap flickering on hex nodes (remove per-byte alternation)
- Fix popup repositioning when moving mouse between lines
- Truncate disasm popup to 6 lines with ... indicator
- Add BUILD_UI_TESTS option to skip widget tests on headless CI
- Add test_disasm with 35 test cases for disassembly and hex dump
- Add KUSER_SHARED_DATA example .rcx file

third_party/fadec/.build.yml

@@ -0,0 +1,16 @@
+image: alpine/edge
+sources:
+- https://git.sr.ht/~aengelke/fadec
+packages:
+- meson
+tasks:
+- build: |
+    mkdir fadec-build1
+    meson fadec-build1 fadec
+    ninja -C fadec-build1
+    ninja -C fadec-build1 test
+    # Complete test with encode2 API.
+    mkdir fadec-build2
+    meson fadec-build2 fadec -Dwith_encode2=true
+    ninja -C fadec-build2
+    ninja -C fadec-build2 test