feat: reduce build size — replace Pillow with cv2, refactor build scripts

- Create utils/image_codec.py with cv2-based image helpers
- Replace PIL usage across all routes, filters, and engines with cv2
- Move Pillow from core deps to [tray] optional in pyproject.toml
- Extract shared build logic into build-common.sh (detect_version, cleanup, etc.)
- Strip unused NumPy/PIL/zeroconf/debug files in build scripts

server/pyproject.toml

@@ -28,7 +28,6 @@ dependencies = [
     "httpx>=0.27.2",
     "packaging>=23.0",
     "mss>=9.0.2",
-    "Pillow>=10.4.0",
     "numpy>=2.1.3",
     "pydantic>=2.9.2",
     "pydantic-settings>=2.6.0",
@@ -46,6 +45,7 @@ dependencies = [
     "sounddevice>=0.5",
     "aiomqtt>=2.0.0",
     "openrgb-python>=0.2.15",
+    "opencv-python-headless>=4.8.0",
 ]
 
 [project.optional-dependencies]
@@ -57,9 +57,11 @@ dev = [
     "black>=24.0.0",
     "ruff>=0.6.0",
     "opencv-python-headless>=4.8.0",
+    "Pillow>=10.4.0",
 ]
 camera = [
-    "opencv-python-headless>=4.8.0",
+    # opencv-python-headless is now a core dependency (used for image encoding)
+    # camera extra kept for backwards compatibility
 ]
 # OS notification capture (winrt packages are ~2.5MB total vs winsdk's ~35MB)
 notifications = [
@@ -78,6 +80,7 @@ perf = [
 ]
 tray = [
     "pystray>=0.19.0; sys_platform == 'win32'",
+    "Pillow>=10.4.0; sys_platform == 'win32'",
 ]
 
 [project.urls]