chore: add initial InternalAI platform installer setup

Add installer scripts and documentation for the InternalAI platform setup repository. This provides a streamlined installation process for the private InternalAI monorepo platform.

+ Add .gitignore with macOS, editor, and temporary file exclusions
+ Add comprehensive README.md with installation instructions, prerequisites, CLI commands, and troubleshooting guide
+ Add install.sh one-liner script that downloads and executes the main setup

.gitignore

@@ -0,0 +1,41 @@
+# macOS
+.DS_Store
+.AppleDouble
+.LSOverride
+
+# Thumbnails
+._*
+
+# Files that might appear in the root of a volume
+.DocumentRevisions-V100
+.fseventsd
+.Spotlight-V100
+.TemporaryItems
+.Trashes
+.VolumeIcon.icns
+.com.apple.timemachine.donotpresent
+
+# Directories potentially created on remote AFP share
+.AppleDB
+.AppleDesktop
+Network Trash Folder
+Temporary Items
+.apdisk
+
+# Editor directories and files
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+.project
+.classpath
+.c9/
+*.launch
+.settings/
+*.sublime-workspace
+
+# Temporary files
+*.tmp
+*.temp
+.cache/