fix(#319,#333): oracle quorum check + reserve tracker duplicate curre…

[hartz0]

closes #319
closes #333

fix(#319, #333): oracle validator quorum check + reserve tracker duplicate currency guard

Summary

Fixes two security issues reported in issues #319 and #333.

Issue #319 — Oracle median with no quorum safety net

update_rate previously allowed 1 or 2 source feeds through as long as some sources were provided, meaning a single
potentially-malicious validator could set the median with no meaningful aggregation. The check now enforces a minimum of
max(min_signatures, MIN_ORACLE_SOURCE_FEEDS=3) sources whenever sources are provided. Passing zero sources (the existing bypass path
for direct rate submission) is unchanged.

Before:

if sources.len() > 0 && sources.len() < MIN_ORACLE_SOURCE_FEEDS {
env.panic_with_error(OracleError::InsufficientOracleSources);
}

After:

if sources.len() > 0 {
let required = min_sigs.max(MIN_ORACLE_SOURCE_FEEDS);
if sources.len() < required {
env.panic_with_error(OracleError::InsufficientOracleSources);
}
}

Issue #333 — Reserve tracker add_currency allows duplicates

add_currency pushed to a Vec without checking for duplicates. A duplicated currency entry causes iteration-based reserve lookups to
count the same reserve twice, inflating the reported total. The function now iterates the stored list before pushing and panics with
DuplicateCurrency (#8008) if the currency is already present.

Changes

• acbu_oracle/src/lib.rs — quorum check uses max(min_signatures, 3) threshold
• acbu_oracle/tests/test.rs — 4 new tests: too few sources panics, exactly 3 succeeds, zero sources bypasses, min_signatures >
  MIN_ORACLE_SOURCE_FEEDS enforces the larger value
• acbu_reserve_tracker/src/lib.rs — DuplicateCurrency = 8008 error; add_currency dedup check; get_currencies getter; DataKey includes
  both last_verify_call and currencies
• acbu_reserve_tracker/tests/test.rs — 3 new tests: add and retrieve currencies, duplicate panics with #8008, non-admin call rejected
• docs/ERROR_CODES.md — regenerated with DuplicateCurrency = 8008

Notes

This branch is based on current dev with no merge conflicts. The old branch fix/319-333-oracle-quorum-reserve-duplicate-currency had a
DataKey conflict (both dev and that branch added a field simultaneously) and an incorrect quorum check that removed the > 0 guard, which would have broken zero-source submissions.

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📒 Files selected for processing (5)

• acbu_oracle/src/lib.rs
• acbu_oracle/tests/test.rs
• acbu_reserve_tracker/src/lib.rs
• acbu_reserve_tracker/tests/test.rs
• docs/ERROR_CODES.md

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[hartz0]

hello maintainer, please merge my pr