Add glyph.h (Debug Visualizer)

[Lightning11wins]

Adds centrallix-lib/include/glyph.h, a set of macros for printing a repeating characters, useful for visualizing how long-running algorithms are progressing.

Glyphs are compiled out unless ENABLE_GLYPHS is defined, which is left commented out.

Split out of #77 at review request.

[greptile-apps]

Greptile Summary

Adds an opt-in debug visualization header for printing recurring glyphs during long-running algorithms.

• Defines enabled and compiled-out forms of the glyph macros.
• Adds the standard-library headers required by the enabled implementation.
• Renames the initializer and printing macros to camel case.
• Documents and asserts that the interval must be greater than zero.

Confidence Score: 5/5

The PR appears safe to merge, with no accepted new findings or outstanding blocking review threads.

The enabled header now includes its required declarations, and the macro rename has no repository callers to break. Lightning11wins dismissed the conditional-caller concern without further context; that resolved thread does not lower merge confidence.

Important Files Changed

Filename	Overview
centrallix-lib/include/glyph.h	Introduces the optional glyph visualizer and updates its dependencies, naming, and interval validation.

_{Reviews (2): Last reviewed commit: "Require interval to be one or more." | Re-trigger Greptile}

[gbeeley]

Looks good, a future improvement might be to make interval time based instead of modulus based, and for glyph() to NOP if the interval has not yet elapsed.