Consolidate docs into one Sphinx project with language subdirectories

Adopt WebRunner's docs layout: a single Sphinx project under
docs/source/ with per-language subdirectories (Eng/, Zh-TW/, Zh-CN/)
and a language-neutral API/ tree. The top-level index.rst is a slim
hero with four toctrees pointing at chapter sub-indexes
(eng_index, zh_tw_index, zh_cn_index, api_index); each sub-index
has chapter sections that toctree to the chapter docs.

Cross-language navigation now works through normal Sphinx toctrees
inside the same build — relative ../html-zh-TW/ links and per-
language RTD projects are no longer needed. Drop the per-language
.readthedocs.zh-*.yaml files, drop the source.zh-TW/ and
source.zh-CN/ source trees, drop the per-language conf.py + index,
and simplify make.bat / Makefile to a single html target.

Single API tree built once from English autodoc avoids the
duplicate object descriptions warnings the three-tree layout
produced.

Author: JE-Chen

.readthedocs.yaml

@@ -1,11 +1,9 @@
 # .readthedocs.yaml
-# Read the Docs configuration file for the English ("fileautomation") project.
-# Sibling files .readthedocs.zh-TW.yaml and .readthedocs.zh-CN.yaml configure
-# the two translation projects. Wire each translation project to its own YAML
-# in the RTD project admin (Settings → Default settings → Path), and link the
-# three projects via the main project's Translations tab.
+# Read the Docs configuration file. The single Sphinx project under
+# docs/source/ builds all three languages into one site (subdirectories
+# Eng/, Zh-TW/, Zh-CN/, and API/) — cross-language navigation works through
+# normal Sphinx toctrees, with no per-language project required.
 # See https://docs.readthedocs.io/en/stable/config-file/v2.html
-#     https://docs.readthedocs.io/en/stable/localization.html
 
 # Required
 version: 2
@@ -16,7 +14,7 @@ build:
   tools:
     python: "3.11"
 
-# Build the English documentation in docs/source with Sphinx.
+# Build the documentation in docs/source/ with Sphinx.
 sphinx:
    configuration: docs/source/conf.py
 

.readthedocs.zh-CN.yaml

@@ -4,21 +4,13 @@ SPHINXBUILD   ?= sphinx-build
 SOURCEDIR     = source
 BUILDDIR      = _build
 
-.PHONY: help html clean html-zh-TW html-zh-CN html-all
+.PHONY: help html clean
 
 help:
 	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS)
 
 html:
 	@$(SPHINXBUILD) -M html "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS)
 
-html-zh-TW:
-	@$(SPHINXBUILD) -b html source.zh-TW "$(BUILDDIR)/html-zh-TW" $(SPHINXOPTS)
-
-html-zh-CN:
-	@$(SPHINXBUILD) -b html source.zh-CN "$(BUILDDIR)/html-zh-CN" $(SPHINXOPTS)
-
-html-all: html html-zh-TW html-zh-CN
-
 clean:
 	@$(SPHINXBUILD) -M clean "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS)

.readthedocs.zh-TW.yaml

@@ -18,27 +18,9 @@ if errorlevel 9009 (
 	exit /b 1
 )
 
-if "%1" == "html-zh-TW" goto build-zh-TW
-if "%1" == "html-zh-CN" goto build-zh-CN
-if "%1" == "html-all" goto build-all
-
 %SPHINXBUILD% -M %1 %SOURCEDIR% %BUILDDIR% %SPHINXOPTS% %O%
 goto end
 
-:build-zh-TW
-%SPHINXBUILD% -b html source.zh-TW %BUILDDIR%\html-zh-TW %SPHINXOPTS% %O%
-goto end
-
-:build-zh-CN
-%SPHINXBUILD% -b html source.zh-CN %BUILDDIR%\html-zh-CN %SPHINXOPTS% %O%
-goto end
-
-:build-all
-%SPHINXBUILD% -M html %SOURCEDIR% %BUILDDIR% %SPHINXOPTS% %O%
-%SPHINXBUILD% -b html source.zh-TW %BUILDDIR%\html-zh-TW %SPHINXOPTS% %O%
-%SPHINXBUILD% -b html source.zh-CN %BUILDDIR%\html-zh-CN %SPHINXOPTS% %O%
-goto end
-
 :help
 %SPHINXBUILD% -M help %SOURCEDIR% %BUILDDIR% %SPHINXOPTS% %O%