Added trace scaling, improved font size scaling, added german lang

[Schildkroet]

DSView Fork — Change Summary

1. Vertical Y-axis Scaling (Ctrl+Shift+Mouse Wheel)

• appconfig.h/cpp — Added persistent traceHeightFactor (range 0.1–20.0) to
  AppOptions; added GetTraceFontSize() helper returning a platform-clamped font size.
• view.h/cpp — Added _trace_height_factor, vzoom(), and get_trace_font_scale();
  signals_changed() multiplies _signalHeight by the factor with a font-aware row-height
  floor.
• viewport.cpp — Ctrl+Shift+wheel routes to vzoom() instead of scrolling; zoom step
  halved for finer control.
• appconfig.cpp — Maximum font size raised from 14 → 16 on Linux.

2. Font and Geometry Scaling

All trace-area paint code had hardcoded 10 px font caps, and label/trigger geometry used
fixed constants. Replaced with dynamic scaling throughout:

• trace.h/cpp — Added get_label_scale(), get_squareWidth(), get_squareMargin(),
  and scaled get_leftWidth() / get_rightWidth() / get_headerHeight().
• logicsignal.cpp — Trigger button boxes and glyph insets scale with get_label_scale().
• viewport.cpp — Hover popup (width / period / frequency) box geometry fully scaled.
• header.cpp — Channel label font uses GetTraceFontSize() * get_trace_font_scale().
• ruler.cpp — Timing bar font: removed 10 px cap, uses GetTraceFontSize().
• protocoldock.cpp — Decoder results table row height set to
  QFontMetrics.height() * 1.5.
• decoderoptionsdlg.cpp — Bottom widget area uses max(hardcoded, dynamic sizeHint)
  to prevent clipping at large font sizes.

3. Translation Fixes

• storesession.cpp — Fixed 12 call sites using the wrong string page
  (STR_PAGE_DLG → STR_PAGE_MSG).
• lang/en/dlg.json, lang/cn/dlg.json — Added 7–8 missing entries for new
  settings UI strings (adaptive font width, vertical scroll action, ruler units, etc.).

4. German Language (de)

• appconfig.h — Added #define LAN_DE 7.
• appconfig.cpp — Auto-detects German system locale.
• langresource.h — Added {7, "de"} to the language key table; is_lang_en()
  returns true for German so decoder parameter names fall back to English gracefully.
• logobar.h/cpp — Added Deutsch menu entry wired to on_actionDe_triggered();
  menu icon updates to the German flag on selection.
• mainwindow.cpp — switchLanguage() handles LAN_DE (removes Qt translators,
  same as English).
• DSView/icons/German.svg — German tricolor flag (black / red / gold).
• DSView/DSView.qrc — Registered German.svg in the resource bundle.
• lang/de/toolbar.json — 47 entries (all menu and toolbar labels).
• lang/de/msg.json — 97 entries (all message box and error strings).
• lang/de/dlg.json — 209 entries (all dialog and UI strings).
• lang/en/toolbar.json, lang/cn/toolbar.json — Added IDS_TOOLBAR_HELP_LANG_DE
  so the menu entry is labelled correctly in English and Chinese UI modes.
• CMakeLists.txt — No change needed; the existing
  install(DIRECTORY lang …) rule already covers lang/de/. Deploy with sudo make install.

[mrehkopf]

Oh neat, I had given up on Qt6 on Windows because of the taskbar progress effect. Same for window dragging on wayland. 😅

[mrehkopf]

I see you might have encountered a pitfall with pull requests (as I have numerous times before) - since you continued pushing to the same branch all your commits have now piled up in this PR. 😆 Is it safe to assume all commits so far are fine for merging or should I cut off at some point?
(Note I'm on summer vacation at the moment so I can't really test anything - will be back in about two weeks)

[Schildkroet]

Yes, i forgot to branch and accidentially used master 😅
All commits are valid and everything is in a working state. You can test it here: https://github.com/Schildkroet/DSView/releases
Currently most of my issues are done, so i guess were won't be much more changes for now.

[mrehkopf]

I took a brief look from a user's perspective (Demo mode only since I didn't bring my DSLogic 😆) and it looks pretty nice, good call matching the LA trace colors with the wire colors by default :) The additional themes are also nice. Can't say a lot about the DSCope changes since I don't own one and never used one.
One thing I noticed about the LA view is that the traces are now separated by horizontal separators. I see how it improves readability for the levels of adjacent traces but for my taste they now consume too much space vertically :D Is there a way to disable them?
Other than that I think a numerical entry option for the vertical zoom factor would be useful (or a way to reset it to 1).