Increase component clearance and add text halo for label visibility

- _LEAD_STUB_LENGTH 1.0 → 2.0: prevents inductor/component bodies from
  overlapping the transistor symbol on complex circuits (Hartley, Colpitts)
- _DEVICE_LABEL_OFST 0.4 → 0.6: pushes Q1 label further from junction
  wires, especially important for PNP layouts
- Add _add_text_halos() SVG post-processor: applies paint-order stroke
  with white halo behind all text so net labels (tap, in, out) remain
  readable when wires cross underneath

backend/src/spicebook/engine/schematic.py

@@ -76,9 +76,9 @@ SUPPLY_NAMES = {"vcc", "vdd", "vee", "vss"}
 _LABEL_OFST = 0.5           # general label offset from component body
 _LABEL_OFST_TIGHT = 0.2     # horizontal single-component paths
 _NET_LABEL_FONTSIZE = 10     # net/node labels (was 8-9)
-_DEVICE_LABEL_OFST = 0.4    # active device body label offset
+_DEVICE_LABEL_OFST = 0.6    # active device body label offset (clear junction wires)
 _PARALLEL_PATH_SPACING = 4.0  # between parallel vertical paths (was 2.5)
-_LEAD_STUB_LENGTH = 1.0     # clearance from transistor pin (was 0.75)
+_LEAD_STUB_LENGTH = 2.0     # clearance from transistor pin to first component
 _INPUT_JUNCTION_LENGTH = 1.5  # base/gate junction wire (was 1.0)
 _VERT_CHAIN_MIN_LEN = 4.0    # minimum component length in vertical chains
 
@@ -1555,6 +1555,33 @@ def _add_graph_paper_bg(svg_str: str, pad: float = 15.0) -> str:
     return ET.tostring(root, encoding="unicode")
 
 
+def _add_text_halos(svg_str: str) -> str:
+    """Add a white halo behind all text elements so labels stay readable
+    over crossing wires.
+
+    Uses paint-order: stroke first, then fill — a thick white stroke
+    behind the text acts as a knockout mask without adding extra elements.
+    """
+    ET.register_namespace("", _SVG_NS)
+    try:
+        root = ET.fromstring(svg_str)
+    except ET.ParseError:
+        return svg_str
+
+    ns = {"svg": _SVG_NS}
+    for text_el in root.findall(".//svg:text", ns):
+        style = text_el.get("style", "")
+        # Skip if already styled (shouldn't happen with SchemDraw output)
+        if "paint-order" in style:
+            continue
+        text_el.set("paint-order", "stroke fill")
+        text_el.set("stroke", _GRID_BG)
+        text_el.set("stroke-width", "4")
+        text_el.set("stroke-linejoin", "round")
+
+    return ET.tostring(root, encoding="unicode")
+
+
 def annotate_svg(svg_str: str, parsed: ParsedNetlist) -> str:
     """Add data attributes to SVG text elements for interactive editing.
 
@@ -1680,8 +1707,9 @@ def netlist_to_svg(netlist_text: str) -> SchematicResult:
     if svg is None:
         svg = _render_grid(parsed)
 
-    # Post-process: graph paper background, then data attributes
+    # Post-process: graph paper background, text halos, then data attributes
     svg = _add_graph_paper_bg(svg)
+    svg = _add_text_halos(svg)
     svg = annotate_svg(svg, parsed)
     component_map = build_component_map(parsed)