Add readVaultSymbol to stellar.ts

[AJtheManager]

Done! I've added both functions to stellar.ts:

1. readVaultSymbol — Reads the vault's share token symbol using the symbol() contract method. Follows the same pattern as readRwaSymbol(), handling both string and Record return types.
2. readEarlyRedemptionFeeBps — Reads the early redemption fee in basis points (e.g., 100 = 1%) using the early_redemption_fee_bps() contract method. Returns a number and follows the pattern of readOperatorThreshold().

Both functions use the existing simulateRead helper and include JSDoc comments explaining their purpose.

closes #683
closes #681

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@AJtheManager Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

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