Fetch JUCE into build/, tidy gitignore, expand README

.gitignore

@@ -1,13 +1,67 @@
-build/
-deps/
-*.o
-*.d
-*.dylib
+# Build output (all build products, including the JUCE dep fetched into build/)
+/build/
+
+# ===== Editors / text tools =====
+# Vim swap + backup files
+*.swp
+*.swo
+*.swn
+*.swx
+*~
+*.~[0-9]*
+# Vim persistent undo history
+*.un~
+
+# Backup / miscellaneous editor files
+*.bak
+*.backup
+*.old
+*.orig
+*.rej
+.patch
+
+# IDE / editor config
+.idea/
+.vscode/
+*.code-workspace
 .DS_Store
-*.dSYM/
-*.vst3/
-*.component/
+
+# ===== CMake / build system =====
 CMakeCache.txt
 CMakeFiles/
 Makefile.cmake
-JuceLibraryCode/
+*.cmake.in
+cmake_install.cmake
+CTestTestfile.cmake
+Testing/
+
+# JUCE generated sources outside build/
+JuceLibraryCode/
+juce_build/
+
+# ===== C / C++ object + coverage artifacts =====
+*.o
+*.obj
+*.a
+*.lib
+*.so
+*.dylib
+*.dll
+*.d
+*.gcda
+*.gcno
+*.profraw
+
+# ===== Plugin/audio output bundles =====
+*.vst3/
+*.component/
+*.bundle/
+*.app/
+*.dSYM/
+*.lv2/
+
+# ===== Logs / transient =====
+*.log
+core
+core.*
+*.pid