Labels: embed Unicode-capable fonts — non-Latin tool names garble on printed labels

[sliptonic]

What to build

Label PDFs (spec_label_sheets.py, label_sheets.py) use ReportLab's base-14 fonts (Helvetica, Courier), which are effectively Latin-1 only. A tool named in Japanese, Chinese, Korean — or even Polish — garbles on a printed label today. Labels are server-rendered artifacts: no client can fix this, so full Unicode fidelity for user data on labels is a core obligation regardless of any translation plans.

Scope:

• Embed a Unicode-capable font family (Noto or DejaVu; needs a bold + regular + mono equivalent for the Courier code line).
• Re-verify _truncate widths and all three painters (compact, roomy, plaque) — text metrics change with the font, and the 0.12.0 roomy layouts were hand-tuned.
• Ratify (glossary/SPEC_LABELS.md one-liner) that spec-line abbreviations (Ø, FL, LOC, OAL, tip, °) are machinist lingua franca and stay untranslated by design.
• Mind container size: font files ship in the Docker image.

Demoable: a tool named 超硬エンドミル 6mm renders correctly on all label stocks.

Acceptance criteria

• CJK and Latin-Extended tool names render correctly on every stock/template
• Truncation still behaves (no overflow, no mid-glyph clipping) on all painters
• Spec abbreviations ratified as untranslated in docs
• Visual spot-check of existing English labels (no layout regression)
• Docker image size impact noted in the PR

Blocked by

None - can start immediately