Wiresheet zoom, from the View menu, the toolbar and Ctrl+wheel

A ladder of scales from 50% to 300%, stepped by Zoom In / Zoom Out / Zoom 100%,
by the two buttons beside the navigation arrows, and by Ctrl and the wheel,
which holds the point under the pointer still. A menu or keyboard zoom holds
the middle of the view instead, so it closes in on what is already being
looked at.

Painting and routing stay at 1:1, because that is where every metric is tuned:
box header and row heights, wire stubs, lane gaps, standoffs, knob radii. Zoom
scales the finished picture, so a zoomed sheet keeps the proportions of a 1:1
one and the router reaches the same decisions at every scale. Text comes along
because the three box fonts are resized once the boxes have been measured with
them.

redraw_links replaces the direct draw_links calls a drag or a drop makes: the
router reads box positions off the canvas, so the boxes go back to 1:1 for the
routing pass and the result is scaled again. Canvas coordinates carry the zoom,
which is why the drag, release and drop handlers now snap against
meta_scale * zoom -- a box dragged the same distance across the screen lands on
the same meta step at 50%, 100% and 200%.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app_state.py

@@ -8,7 +8,7 @@ so later rebinding would only ever be seen by the module that did it.
 import configparser
 import os
 
-VERSION = "0.0.0.032"
+VERSION = "0.0.0.033"
 PROPERTIES_FILE = os.path.join(os.path.dirname(os.path.abspath(__file__)), "editor.properties")
 DEFAULT_GRID_SIZE = 10
 DEFAULT_ADD_TIMESTAMP = True
@@ -53,6 +53,7 @@ link_mark_element = None      # Component marked as a link endpoint via "Link Ma
 selected_link_tag = None      # Canvas tag of the currently selected (red-highlighted) link wire
 unroutable_link_count = 0     # Links drawn as knobs because no wire could avoid a component
 meta_scale = DEFAULT_GRID_SIZE  # Pixels per meta coordinate step on the painted sheet
+zoom = 1.0                    # Scale the open sheet is painted at; 1.0 is one pixel per pixel
 knob_link_ends = {}           # wire tag -> (x1, y1, x2, y2) for a link shown as two knobs
 canvas_link_map = {}          # Canvas link tag -> ET.Element (<link>)
 xml_root_element = None       # Keep a persistent root reference to redraw tree layouts cleanly