Feature idea: quick reset buttons for auto-numbering counters

[ispyisail]

Forum thread: https://qelectrotech.org/forum/viewtopic.php?pid=16926#p16926

Problem

Resetting an active numbering counter (conductor, element, or folio) back to a starting value is something that happens very often during diagram work — starting a new sheet/section and wanting labels to restart at "1", or marking a run of items as "not yet assigned" pending manual numbering. Today that requires the full round trip through the project properties dialog: open it from the Autonum dock's "Configure" button, locate the right numbering context, select the specific part row, clear and retype the value in its field, and confirm — roughly seven actions for what's conceptually a single "reset" click.

What exists today

• The "Auto numbering" dock (AutoNumberingDockWidget, sources/autoNum/ui/autonumberingdockwidget.*) already shows one combo box each for the active Conductor/Element/Folio numbering context (m_conductor_cb/m_element_cb/m_folio_cb) plus a single "Configure" button (on_m_configure_pb_clicked(), autonumberingdockwidget.cpp:333-341) that opens ProjectPropertiesDialog on its Autonum page — a full detour through the general project-properties dialog for what is often a one-value tweak.
• QETProject stores each category's set of named numbering contexts as QHash<QString, NumerotationContext> (conductorAutoNum()/elementAutoNum()/folioAutoNum(), qetproject.h:149-151), and exposes addConductorAutoNum(key, context) / addElementAutoNum(...) / addFolioAutoNum(...) (qetproject.h:152-154) to write a context back — the same setters the config dialog itself uses, already wired to the change signals (conductorAutoNumChanged etc.) that keep the dock in sync.
• NumerotationContext::replaceValue(int index, QString content) already exists specifically to overwrite one part's value in place while preserving its type/increase/initialvalue/modulus — exactly the primitive a "reset" action needs, without touching the rest of the context's configuration.
• Folio-anchored part types (unitfolio/tenfolio/hundredfolio) already carry an explicit initialvalue field per part (NumerotationContext::addValue) — the value a "reset to start" action would restore for those specifically, rather than a hardcoded "1".

Proposed scope

Add two small buttons next to each of the three combo boxes on the dock widget itself, skipping the configure dialog entirely for the common case:

• Reset to start: for the context currently selected in that category's combo box, call replaceValue() on every part with a sensible per-type starting value — the part's own initialvalue where one exists (folio-anchored types), "1" for plain numeric types, "a"/"A" for the alphabetic part type — then write the updated context back via the matching addConductorAutoNum/addElementAutoNum/addFolioAutoNum call so the existing refresh signals fire as normal.
• Reset to "?": same mechanism, but sets every part's value to the literal placeholder "?", for marking a run of items as "needs manual numbering" without picking a specific starting value.

The original request's third idea (a small popup to type an arbitrary starting value) is effectively today's config-dialog value field made quicker to reach — proposing to fold that into a lightweight popup anchored to the dock's combo box rather than a third button per category, but open to a literal third button if that's preferred.

Related, not proposed here

The forum thread's second request (a live X/Y position readout while dragging elements) was already implemented separately and isn't part of this proposal.

Happy to build this if the scope above sounds right.

[ispyisail]

Opened a PR implementing the scope above: #626