Replace hand-built board with XiaoBoard from @tscircuit/common

[js360000]

Summary

feat: replace hand-built board with XiaoBoard from @tscircuit/common (#2)

Adopt the shared XIAO breakout from the new @tscircuit/common module
instead of maintaining the bespoke PinOutCircuit stamp-board chip
inline. The Waveshare RP2040-Zero is a XIAO-form-factor board, so the
upstream component already encodes the correct edge pad layout, pin
labels, schematic arrangement, and plated-hole geometry.

Changes:

• Add @tscircuit/common@^0.0.42 to dependencies.
• index.tsx: replace <board> + <PinOutCircuit /> with
  <XiaoBoard variant="RP2040" withPlatedHoles boardProps={…}> and
  hold the remaining subcircuits (VoltageRegulator, LedCircuit,
  FlashCircuit, CrystalCircuit, RP2040Circuit) as children. Pass the
  existing routingDisabled + schMaxTraceDistance flags through
  boardProps so the previous board-level behaviour is preserved.
• __snapshots__/: add PCB + schematic snapshots produced by
  tsci snapshot index.tsx so the new top-level can be regression-
  tested against future XiaoBoard upstream changes.

PinOutCircuit is left in lib/ untouched — keeping the file in the
tree avoids breaking any out-of-tree imports while the migration
settles, and the lib component is no longer instantiated from
index.tsx.

bun run build and bunx tsci snapshot index.tsx succeed locally.
The two key-prop warnings under XiaoBoardFootprint and
RP2040Circuit are pre-existing render-time warnings inside those
components and are not introduced by this change.

Closes #2

Diff

 __snapshots__/index-pcb.snap.svg       |   1 +
 __snapshots__/index-schematic.snap.svg | 104 +++++++++++++++++++++++++++++++++
 bun.lock                               |   6 ++
 index.tsx                              |  12 ++--
 package.json                           |   3 +
 5 files changed, 121 insertions(+), 5 deletions(-)

Claim

/claim #2