`BoardOutlineCommands.add_mounting_hole` produced footprints with an empty
library:name id (`(footprint "" ...)` in the .kicad_pcb), which KiCad's GUI
Move tool refuses to select — users couldn't drag the resulting MHs in the
editor. It also emitted the pad with the default `*.Cu` + `*.Mask` LSET on
NPTHs; with `padDiameter > diameter` that creates phantom copper annular
rings on every Cu layer and trips clearance DRC against neighbouring nets.
Repro: call `add_mounting_hole` with `position={x:117,y:84.5,unit:"mm"},
diameter:3.2, padDiameter:3.5`. The resulting MH is unselectable and DRC
reports phantom F.Cu pad shorts to neighbouring component pads.
Changes:
- Set a real FPID via `module.SetFPID(pcbnew.LIB_ID(lib, name))`. Default
is `MountingHole:MountingHole_<diameter:g>mm` (e.g. 3.2 → 3.2mm); a new
optional `footprintLibId` parameter overrides.
- For NPTH (the default `plated:false`), restrict the pad's LSET to
`F.Mask` + `B.Mask` only. PTH path is unchanged — the default Cu+Mask
LSET is correct there.
- Update the schema in `tool_schemas.py`: previously advertised
`x`/`y`/`diameter` at the top level, but the impl reads
`position={x,y,unit}`, `padDiameter`, `plated`. Schema now matches the
implementation and exposes the new `footprintLibId` param.
- New `tests/test_add_mounting_hole.py` regression suite (7 tests) asserting
SetFPID is invoked with non-empty lib:name (default + override forms),
NPTH SetLayerSet excludes any Cu layer, and PTH does not call
SetLayerSet (preserves default Cu+Mask).
