fix: convert cf-kv and excalidraw-libraries from submodules to regular files

- Remove stale cloudflare-worker submodule entry from .gitmodules
- Remove .git dirs from cf-kv and excalidraw-libraries so Git tracks them as regular files
- Fixes 'No url found for submodule path cf-kv' CI error

excalidraw-libraries/stats/2021-01/2021-01-28.json

@@ -0,0 +1,23 @@
+{
+  "dbssticky-data-viz": 31,
+  "drwnio-drwnio": 100,
+  "drwnio-storytelling": 38,
+  "dwelle-hearts": 6,
+  "excacomp-mobile-kit": 33,
+  "excacomp-web-kit": 46,
+  "franky47-apple-devices-frames": 10,
+  "g-script-android": 6,
+  "g-script-charts": 13,
+  "g-script-forms": 43,
+  "g-script-medias": 10,
+  "h7y-dropdowns": 21,
+  "inwardmovement-information-architecture": 34,
+  "lipis-polygons": 7,
+  "lipis-stars": 11,
+  "maeddes-technology-logos": 94,
+  "morgemoensch-gadgets": 9,
+  "pclainchard-it-logos": 23,
+  "revolunet-raspberrypi3": 7,
+  "youritjang-software-architecture": 105,
+  "youritjang-stick-figures": 46
+}