docs: bring datasheet/ into the main repo under hardware/v2/docs

Was a separate, untracked directory (DataSheet/) outside the repo.
Renamed to lowercase and moved in as hardware/v2/docs/datasheet/, with
its own .gitignore for LaTeX build byproducts (compiled PDFs stay
tracked, .aux/.log/.toc/etc do not). Now versioned and shares this
repo's own remote instead of living untracked on disk.

Content: IT+EN LaTeX chapter sources, reference manufacturer PDFs, and
compiled datasheet PDFs including the 2026-09-07 SDRAM upgrade
addendum (AS4C32M16SB-7BIN part/pinout/timing) in the v2-en chapters.

Note: hardware/v2/docs/DatasheetLatex/ (and the v1 sibling) is a
separate, already-tracked, differently-structured LaTeX document that
predates this move -- left untouched, not merged, since its chapter
set and content differ and merging was not requested.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v

.gitignore

@@ -0,0 +1,21 @@
+# LaTeX build artifacts (latexmk et al.) -- sources and rendered PDFs
+# are versioned, intermediate build byproducts are not.
+*.aux
+*.log
+*.out
+*.toc
+*.lof
+*.lot
+*.fls
+*.fdb_latexmk
+*.synctex.gz
+*.bbl
+*.bcf
+*.blg
+*.run.xml
+*.nav
+*.snm
+*.vrb
+
+# macOS
+.DS_Store