fix: repair broken internal links across four patterns

[pfeerick]

Summary

Fixes the four distinct classes of broken relative links identified during the pre-merge gap analysis against the official EdgeTX Lua reference guide (Finding 2 of that review):

• Mangled GitBook-artifact placeholder link — a stray <!-- LUADOC:BEGIN lcd -->-style comment got slugified into a literal, non-existent path (../lcd-functions-less-than-greater-than-luadoc-begin-lcd/lcd_functions-overview.html) across every lcd-draw-*/lcd-get-color/lcd-set-color/etc. page. Now points at api-reference/display-lcd.md, or api-overview/constants/color-constants.md#indexed-colors on the two lines where the color table is the actual referent (matching the anchor already used correctly elsewhere, e.g. programming/core-concepts/drawing-flags-and-colors.md).
• Broken appendix references — ../appendix/units.html and ../../part_vii_-_appendix/fonts.md pointed at a directory that doesn't exist in this site. Now point at api-overview/constants/units.md and api-overview/fonts.md. Also fixes a stray extra pair of parens around the units.html link in runtime-play-number.md and runtime.d.lua ([Full list]((../appendix/units.html))).
• Assumed topic subfolders under api-reference/ — several links assumed nesting like api-reference/variables/runtime-get-value.md that doesn't exist; all detail pages are flat directly under api-reference/. Flattened.
• Off-by-one relative path in programming/basics/editor.md — linked to ../../../assets/luals/*.d.lua (one level too many, landing outside md-docs/); corrected to ../../assets/luals/*.d.lua.

Scope note: the review-*.md QA scratch pages and module-*.md dashboards carry duplicate copies of some of these same broken strings but are intentionally left untouched — they're throwaway extraction/review artifacts, not hand-maintained prose, and are slated for exclusion from the production build separately (mkdocs.yml/mkdocs.dev.yml public/dev split).

Test plan

• mkdocs build --strict — exit 0, zero warnings
• Verified every fix target file actually exists at the corrected path before rewriting the link
• Confirmed the #indexed-colors anchor matches the slug already used correctly elsewhere in the site for the same section
• Swept the full website/md-docs tree afterward to confirm zero remaining matches for any of the four broken patterns outside review-*.md/module-*.md

🤖 Generated with Claude Code

https://claude.ai/code/session_015yCHydHbzZYCKpav38SonD