fix: number msop and son right-column pins counterclockwise

[chayan-1906]

Summary

msop and son numbered their right-column pins top→bottom (same direction as the left column), instead of the standard counterclockwise order every other dual-row footprint in this repo uses (soic/dfn/sop8 via getCcwSoicCoords, tssop/ssop in their own coord functions). The pad positions were fine — only the pin→pad mapping was mirrored, so pins 5↔8 / 6↔7 (msop8, son8), 4↔6 (son6), 6↔10 / 7↔9 (msop10) would route to the wrong nets. This never showed in SVG snapshots because pin numbers aren't rendered there.

Fixes #677

Expected vs actual (msop8, default params)

pin	before	after	soic8 for reference
5	y = +0.975 (top-right ❌)	y = −0.975 (bottom-right)	y = −1.905 (bottom-right)
8	y = −0.975 (bottom-right ❌)	y = +0.975 (top-right)	y = +1.905 (top-right)

Changes

• src/fn/msop.ts / src/fn/son.ts: one-line fix in the coord helpers — the right column now runs bottom→top (vssop already worked around this same helper by remapping pin numbers, which is why it wasn't affected)
• tests/msop.test.ts / tests/son.test.ts: added counterclockwise-numbering assertions for msop8, son8, son6 so this can't regress invisibly again

Testing

• New tests fail on main (verified by running them against the unfixed code) and pass with the fix
• Full suite: 434 pass, 0 fail — no snapshot changes (layout is visually identical, only pin numbering changed)
• Pin 1 / silkscreen / courtyard are computed from pin 1 and spans, so they're unaffected
• bun run build and bunx biome format clean

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