Add FloorPlan.DetectFloorPlanFromImage node for raster-to-geometry floor plan detection

[Copilot]

Dynamo users working with raster floor plan images (JPG scans, screenshots, exported sheets) currently have no first-party path to geometry — requiring manual tracing or custom Python. This adds a FloorPlan.DetectFloorPlanFromImage zero-touch node in Core > Geometry that runs a full image processing pipeline and returns Dynamo-native geometry as single lines representing the sketch.

New file: src/RhythmCore/Geometry/FloorPlan.cs

Processing pipeline (pure C#, System.Drawing — no native OpenCV binaries):

• Grayscale via integer fixed-point BT.601 ((77R + 150G + 29B) >> 8)
• 5×5 Gaussian blur denoising
• Thresholding: Otsu automatic or adaptive local-mean (integral image, O(1) per pixel)
• Morphological opening (erode → dilate) for speckle removal
• Sobel edge detection
• Standard Hough transform with peak NMS + per-line segment extraction
• BFS flood-fill room contours with RDP polygon simplification
• Horizontal/vertical wall-gap scan for opening detection

Inputs: imagePath, scale, threshold, adaptiveThreshold, minLineLength, detectRooms, detectOpenings, debugOutput

Outputs (MultiReturn):

Port	Type	Description
lines	Line[]	Detected sketch linework (single centerline lines)
roomBoundaries	PolyCurve[]	Closed room boundary candidates
openingLocations	Point[]	Door/window gap midpoints
report	Dictionary	Dimensions, threshold used, counts, processingTimeMs, warnings[]

Error handling: all failure modes (missing file, unreadable image, sub-50px resolution, zero geometry detected) surface as warnings entries rather than exceptions — node never crashes Dynamo.

Implementation notes:

• No wallThicknessRange — the node returns single lines representing the sketch geometry, not wall thickness estimates.
• Uses global:: aliases (SMath, SysBitmap, ImagePoint, etc.) to resolve ambiguity with the existing Rhythm.System and Rhythm.Math namespaces in the project.
• Large images (>1500px) are downsampled before the Hough accumulator pass to keep processing bounded.
• No native binary deployment concern: System.Drawing is already available via UseWindowsForms=true across all target frameworks (net48 for R20–R24, net7/net8-windows for R25–R27).

[johnpierson]

@copilot, no need for wall thickness estimation, we just want single lines that represent the sketch

[Copilot]

@copilot, no need for wall thickness estimation, we just want single lines that represent the sketch

Removed the wallThicknessRange parameter in bfa8149. The node now only returns single Line geometry from Hough line detection — no wall thickness estimation.