fix(token): validate numeric input in formatAmount to prevent NaN/Infinity

[jaffarkeikei]

What changed? Why?

formatAmount now validates input and returns empty string for invalid values instead of "NaN" or "∞".

Notes to reviewers

Without validation:

formatAmount('abc')       // Returns "NaN" ❌
formatAmount('Infinity')  // Returns "∞" ❌

With fix:

formatAmount('abc')       // Returns "" ✓
formatAmount('Infinity')  // Returns "" ✓

Uses Number.isFinite() to catch both NaN and Infinity.

How has it been tested?

Manual testing with edge cases:

• Non-numeric strings: returns empty string
• Infinity: returns empty string
• Valid numbers: formatted correctly

[cb-heimdall]

🟡 Heimdall Review Status

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