feat: Add wire.breakout element for bus fan-out diagrams

Introduces wire.breakout: a 45° diagonal line of configurable length
(default 1em) that starts at a given (x, y) and exposes a port anchor
<id>-port-<id> at its end point so wires can attach to it as if it were
a block port. A synthesized <id>.center anchor is placed opposite the
configured port-side so wire.wire with style "u-shape" can auto-detect
the port's cardinal side.
- x/y accept number, (rel:, to:) and (from:) forms; (from:) sets the
  start point to the referenced anchor's coordinate.
- direction: one of north-east/north-west/south-east/south-west.
- Optional label positioned via name-pos (NE/NW/SE/SW); when name-pos is
  opposite to direction, the label falls back to the start point so it
  never covers the diagonal line. Label padding matches wire.wire (3pt).
Also adds three examples (breakout, breakout-label, breakout-wire) in
doc/examples.typ referenced from the docstring so tidy auto-renders
them in the manual, and a gallery entry (gallery/test_breakout.typ)
demonstrating orthogonal bus fan-out with breakouts in all four
directions.

doc/examples.typ

@@ -81,6 +81,81 @@ wire.stub("p", "south", name: "south", length: 15pt)
 wire.stub("p", "west", name: "west", length: 3em)
 ```)
 
+#let breakout = example(```
+// 16 breakouts: 4 directions × 4 label positions, laid out
+// two per row so the labels have room to breathe.
+let dirs = ("north-east", "north-west", "south-east", "south-west")
+let poss = ("north-east", "north-west", "south-east", "south-west")
+let short = (
+  "north-east": "NE", "north-west": "NW",
+  "south-east": "SE", "south-west": "SW",
+)
+let cols = 2
+let dx = 5
+let dy = 2
+for (i, dir) in dirs.enumerate() {
+  for (j, pos) in poss.enumerate() {
+    let n = i * poss.len() + j
+    let r = calc.floor(n / cols)
+    let c = calc.rem(n, cols)
+    draw.circle((c * dx, -r * dy), radius: .05)
+    wire.breakout("b" + str(n),
+      x: c * dx, y: -r * dy,
+      direction: dir,
+      port-side: if dir.ends-with("east") { "west" } else { "east" },
+      name: short.at(dir) + "/" + short.at(pos),
+      name-pos: pos)
+  }
+}
+```)
+
+#let breakout-label = example(```
+// name-pos matches direction → label sits at the end point.
+wire.breakout("b1", x: 0, y: 0, direction: "north-east",
+              port-side: "east",
+              name: "at end", name-pos: "north-east")
+
+// name-pos opposite to direction → label would cover the line, so
+// it falls back to the start point.
+wire.breakout("b2", x: 4, y: 0, direction: "north-east",
+              port-side: "east",
+              name: "at start", name-pos: "south-west")
+```, vertical: true)
+
+#let breakout-wire = example(```
+// Bus fan-out: a horizontal wire from the left block to the lower
+// right block carries the full 10-bit bus. A breakout in the middle
+// of that wire taps bits [9:5] and routes them to the upper right
+// block via an L-shaped zigzag (up, then right).
+element.block(x: 0, y: 0, w: 2, h: 2, id: "src",
+  fill: util.colors.blue,
+  ports: (east: ((id: "out"),)))
+element.block(x: 6, y: 0, w: 2, h: 2, id: "dstL",
+  fill: util.colors.green,
+  ports: (west: ((id: "in"),)))
+element.block(x: 6, y: 4, w: 2, h: 2, id: "dstU",
+  fill: util.colors.orange,
+  ports: (west: ((id: "in"),)))
+
+// Full bus wire, labelled "[9:0]" on the left.
+wire.wire("wbus", ("src-port-out", "dstL-port-in"),
+          name: "[9:0]", name-pos: "start")
+
+// Breakout tapped from the midpoint of the bus.
+wire.breakout("tap",
+  x: (rel: 2, to: "src-port-out"),
+  y: (from: "src-port-out"),
+  direction: "north-east",
+  port-side: "west",
+  name: "[9:5]", name-pos: "north-east")
+
+// L-shaped wire from the breakout up and then right to the upper
+// block's input.
+wire.wire("wtap", ("tap-port-tap", "dstU-port-in"),
+          style: "zigzag", zigzag-dir: "horizontal",
+          zigzag-ratio: 100%)
+```)
+
 #let gate-and = example(```
 gates.gate-and(x: 0, y: 0, w: 1.5, h: 1.5)
 gates.gate-and(x: 3, y: 0, w: 1.5, h: 1.5, inverted: "all")