fix(wallet): round instead of truncate in micro-denom conversion

[memosr]

Summary

toMicroDenom (templaterFunctions.ts) and toMicro (useDenom.ts) convert a
user-entered display amount into the chain's base unit by multiplying by the denom
factor and calling Math.floor. The intermediate product is an IEEE-754 double, so
amounts whose decimal expansion is not exactly representable land just below the true
integer and are truncated one micro-unit low.

The deprecated toBaseDenom, which toMicroDenom was introduced to replace, used
.toFixed(0) and rounded correctly. This change restores that behavior.

Reproduction

input	current (Math.floor)	expected
2.01	2009999	2010000
4.02	4019999	4020000
8.29	8289999	8290000
16.08	16079999	16080000

Across all 100,000 two-decimal values from 0.01 to 1000.00, Math.floor is off by one
micro-unit for 1,196 of them (1.20%). Math.round is exact for all 100,000.

Why it matters

toMicroDenom is referenced 25+ times in manifest.json across the send, stake, DAO
deposit and swap flows, and for transaction fees.

• A user who types 2.01 CNPY signs a transaction for 2009999 uCNPY, with no indication
  that the amount was adjusted.
• Swap and order flows compare requestedAmount for an exact match, so an order that is
  one micro-unit short does not match.
• Fees are checked against minFee in fsm/swap.go; a fee at the boundary rounds down
  and the transaction is rejected without a clear reason.

Changes

• cmd/rpc/web/wallet/src/core/templaterFunctions.ts - toMicroDenom uses Math.round.
• cmd/rpc/web/wallet/src/hooks/useDenom.ts - toMicro uses Math.round.

Notes

Math.round on the double product is exact for the value range the wallet handles. A
fully exact fix would use string-based decimal shifting and avoid floating point
entirely. I kept this minimal and behavior-preserving, but happy to follow up with that
if you would prefer it.

tsc --noEmit passes on the wallet package.