feat(pipeline): add @common/@commonparams shared parameter blocks

[pfeerick]

Summary

The in-flight LVGL firmware annotation work (EdgeTX/edgetx#7771) repeats the same 9-line "common object properties" bullet list (x, y, w, h, color, pos, size, visible, floating) verbatim across 27+ widget-constructor luadoc comments, since there was no way to define it once and reference it from many functions. Any future change to those shared properties (this already happened once, for a version-citation fix) requires editing every single occurrence.

Adds two new luadoc tags to tools/docs_pipeline.py:

• @common <name> defines a reusable, non-callable chunk of luadoc body text. It's never treated as an API item — no generated page, no nav entry, no hub-page card. Example:

  /*luadoc
  @common lvgl_object
  
   * `x` (number) position relative to the top-left of the parent
   * `y` (number) position relative to the top-left of the parent
   ...
  */
  

• @commonparams <name> used inside a @function block's parameter section textually splices in the matching @common block's body, before normal @param/@retval parsing runs:

  @param params (table):
  @commonparams lvgl_object
   * `text` (string or function) text to display, defaults to an empty string
  

This works at the text level (splicing into the raw block before parsing), not as a structured-parameter-array merge after parsing — because the existing convention documents each settings table as a single @param params (table): * bullet * bullet ... entry, not one @param per field. Expansion has to happen before that bullet-list text collapses into one flat description string.

extract_model() now does two passes: collect all @common definitions first, then expand @commonparams references and parse @function blocks as normal. Fails loudly (matching this project's own stated extractor design goal) if a @commonparams reference points at an undefined @common block; warns if a @common block is defined but never referenced.

Also fixes a real, unrelated bug found while testing this against the LVGL branch's actual content: FUNCTION_RE/PARAM_RE/RETVAL_RE/NOTICE_RE/STATUS_RE all anchored ^@tag at true column 0, but the LVGL functions are indented 2 spaces (nested inside a table registration block) — every one of PR #7771's ~45 functions was silently extracting zero parameters and "unknown" availability before this fix. FUNCTION_RE itself didn't need the fix (extract_blocks() already strips the whole block, so the first tag always lands at column 0), but the other four did.

Test plan

• New @common/@commonparams syntax unit-tested against a small standalone fixture — confirms expansion works, @common blocks don't become items, undefined references fail loudly, unused definitions warn
• Converted PR #7771's LVGL branch content to use @commonparams in all 27 occurrences and diffed the full rendered output (Markdown + LuaLS .d.lua) before/after — every difference across all 33 changed files is either a source line number (which genuinely shifted) or a generation timestamp; zero content differences
• mkdocs build --strict (public + dev configs) — both pass clean, confirming no regression to any non-LVGL content

🤖 Generated with Claude Code

https://claude.ai/code/session_015yCHydHbzZYCKpav38SonD

[pfeerick]

Superseded by direct work on edgetx_2.12: the extraction-phase indentation fix and @common/@commonparams support from this PR were ported (not merged as-is, since this branch predated later work on that same branch — the page-path/generated-file-marker/dual-luals-output changes) in commit a408cce. See that commit message for the exact scope of what was and wasn't carried over.