test(contract): add invariant coverage for fee_bps upper bound

[Ajibose]

Closes #1244

Summary

set_fee (lib.rs:2715) is the admin entry point for updating the protocol fee. The issue reported that it did not clamp/reject fee_bps values above 10000 (100%), which would make fee computation (amount * fee_bps / 10_000) exceed the transferred amount and could brick tip/pool flows.

Findings

On inspection, set_fee already calls validate_protocol_fee(&env, fee_bps) (lib.rs:2720), which delegates to validate_u32_range(env, "fee_bps", fee_bps, 0, MAX_FEE_BPS) (validation.rs:159-161) with MAX_FEE_BPS = 10_000 (validation.rs:11). This already rejects (panics on) any fee_bps > 10_000 and leaves the previously stored value untouched, since the panic occurs before env.storage().instance().set(&FEE_BPS, &fee_bps) is reached.

So the enforcement described in the issue is already present in the production code. What was missing was explicit test coverage proving the invariant 0 <= fee_bps <= 10_000 holds, per the issue's acceptance criteria ("Invariant test added"). This PR adds that coverage.

Files Changed

Modified:

• packages/contracts/contracts/linkora-contracts/src/test.rs — unit tests for set_fee boundary/rejection behavior
• packages/contracts/contracts/linkora-contracts/src/tests/invariants.rs — dedicated invariant tests for the fee_bps bound

No changes were needed to lib.rs, since the guard already existed there.

Tests Added

In src/test.rs:

• test_set_fee_max_boundary_valid — setting fee_bps = 10_000 (the maximum, 100%) succeeds and is stored correctly.
• test_set_fee_rejects_value_above_max — setting fee_bps = 20_000 panics with "fee_bps must be between 0 and 10000".
• test_set_fee_rejects_value_above_max_leaves_stored_fee_unchanged — after a valid fee is set, an out-of-range update panics and the previously stored fee is left untouched (no partial/corrupted state).

In src/tests/invariants.rs:

• test_invariant_fee_bps_bounded_at_boundaries — asserts both boundary values (0 and 10_000) are accepted and stored as-is.
• test_invariant_fee_bps_never_exceeds_max — asserts an admin misconfiguration (fee_bps = 20_000) is rejected outright (not clamped) and that the stored fee remains at its last valid value.

How to Test

From packages/contracts/contracts/linkora-contracts:

cargo test --lib fee_bps
cargo test --lib set_fee

All new tests pass. The full cargo test --lib suite has 16 pre-existing failures in unrelated tip_* tests (confirmed present on main prior to this change, unaffected by this PR).

CI Green-up (unrelated pre-existing breakage)

This branch was rebased onto the current main (was 46 commits behind), which surfaced that main's HEAD is itself red on Unit Tests / Lint / JS-TS typecheck, unrelated to fee_bps. Fixed alongside this PR so it can merge green:

• rustfmt drift: CI's rustc 1.98.0 formats a few unrelated spots in lib.rs/test.rs differently than the version these files were last formatted with. Reformatted under 1.98.0 to match CI.
• packages/sdk lint errors: unused imports in events-drift.test.ts, a dead callCount in health.test.ts, and any/require() usage in write.test.ts (scoped with the same eslint-disable convention already used elsewhere in the package for legitimate mock reflection).
• packages/sdk typecheck errors: client.ts was missing the scvU64/scvSymbol helpers already present in generated/client.ts, used by prepareLikePostTx/prepareTipTx/preparePoolDepositTx. events/types.ts declared post_id as number on three event interfaces while every other post_id in the codebase (including elsewhere in this same file) is bigint.
• packages/sdk test failures, unmasked once typecheck was fixed (previously the JS/TS job never got far enough to run pnpm test):
  • write.test.ts's @stellar/stellar-base mock had Account: jest.fn() with no implementation, so the asserted _accountId was never actually set on constructed instances.
  • ConnectionHealthMonitor.scheduleCheck's initial-check jitter used Math.random() * backoffMs (default 1000ms) instead of a small interval-scaled jitter, so the "immediate" first health check could be delayed up to a full second — racing past health.test.ts's 500ms waitFor and, once one test timed out before reaching monitor.stop(), leaking a live real-timer loop that polluted call counts in every later test in the file.

None of this is related to the fee_bps invariant fix itself — it's cleanup needed to get a green CI run on top of current main.

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[devJaja]

@Ajibose

Resolve the conflicts please