ENH: Write Image color table, axis flip, and physical scale bar

[imikejackson]

Summary

Extends the Write Image filter with color-table generation, broader type support, format-aware validation, an output flip, and a physical scale bar. Closes #1617. Closes #786.

• Inline color table — a Create Color Table option converts a single-component array to an RGB image using a color preset at write time, removing the need to chain a separate Create Color Map filter. Colorization is streamed one slice at a time (no full RGB volume held in memory) and shares the normalization/interpolation code path with Create Color Map, so the output is identical to running the two filters in sequence.
• Optional mask — masked voxels are written with a user-specified color; the mask is genuinely optional in color-table mode.
• All numeric input types for color-table mode (int8 … float64).
• Format-aware write-type validation — preflight now rejects a (format, data type) combination the backend cannot write (for example, a float32 array to PNG) instead of failing partway through writing. The image backends are the single source of truth for their writable types (stb = uint8; libtiff = uint8/uint16/float32).
• Optional output-image flip — None / Flip About X Axis / Flip About Y Axis, applied only to the written image files; the input Image Geometry and its data arrays are left unmodified. Works across the raw-write path, the color-table path, and all three slice planes.
• Physical scale bar (ENH: Filter to add a physical measurement bar to an image #786) — an Add Physical Scale Bar option appends a white band below each written image containing a left-justified black bar with the length label on the same line (for example 50 µm). The bar length is chosen automatically (largest 1/2/5×10ⁿ value ≤ 25% of the physical image width, from the Image Geometry's spacing) and the label units come from the geometry's length unit, rescaled to a readable SI prefix. The band is appended — image pixels are never covered — and the written file becomes 8-bit RGB. Requires uint8 input (1/3/4 components) or Create Color Table; validated during preflight along with the geometry spacing. Flip composes correctly: the bar stays upright at the bottom.
• Filter documentation updated for all of the above.

Internally, the control-point interpolation and normalization were extracted into shared ColorTableUtilities helpers (with a min == max divide-by-zero guard), and Create Color Map was refactored onto them so both filters use one implementation. For the scale bar, the vendored canvas_ity 2D canvas library and the Lato Regular embedded font moved from OrientationAnalysis to the core simplnx library (build-tree include only, nothing new installed), and the measurement/rendering logic lives in a new unit-tested ScaleBarRenderer core utility.

Test Plan

• SimplnxCore unit tests pass (906/906), including new Write Image cases: color-map parity against the Create Color Map + Write Image chain, all ten numeric input types, the format/type preflight matrix, optional mask, constant-array (min == max) handling, and X/Y flip round-trips read back from disk.
• Scale-bar coverage: 4 ScaleBarRenderer core test cases (nice-length picker, SI-prefix label formatter, band height, band rendering with exact pixel probes) and 4 new Write Image cases (grayscale/RGB/color-table/XZ-plane write→read-back with exact bar-position assertions, flip composition, preflight accept/reject matrix). 12/12 WriteImage + 4/4 renderer tests pass.
• Out-of-core build/tests (not yet run in this branch)