docs: document noise file origins by platform

Author: paul-fresquet

docs/specs/SPEC-noise-file-detection.md

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+# Noise File Detection Specification
+
+## Purpose
+
+This document lists the known noise file names filtered by the client inventory pipeline and their platform origin.
+
+## Known noise file names
+
+| File name | Origin platform | Typical purpose |
+| --- | --- | --- |
+| `desktop.ini` | Windows | Folder customization metadata |
+| `thumbs.db` | Windows | Thumbnail cache |
+| `ehthumbs.db` | Windows | Media Center thumbnail cache |
+| `ehthumbs_vista.db` | Windows | Vista Media Center thumbnail cache |
+| `.desktop.ini` | Windows/Linux legacy compatibility | Legacy hidden variant |
+| `.thumbs.db` | Windows/Linux legacy compatibility | Legacy hidden variant |
+| `.DS_Store` | macOS | Finder metadata |
+| `.AppleDouble` | macOS | Resource fork metadata |
+| `.LSOverride` | macOS | Launch Services overrides |
+| `.Spotlight-V100` | macOS | Spotlight indexing data |
+| `.Trashes` | macOS | Trash metadata or folder marker |
+| `.fseventsd` | macOS | File system event metadata |
+| `.TemporaryItems` | macOS | Temporary items marker |
+| `.VolumeIcon.icns` | macOS | Custom volume icon |
+| `.directory` | Linux (KDE) | Directory display metadata |
+
+## Matching behavior
+
+- On Linux, matching is case-sensitive.
+- On non-Linux platforms, matching is case-insensitive.