feat: add bounded batch contribution read view

[webmirroring]

Closes #553.

Summary

• Added MAX_INVESTOR_READ_BATCH and a pure read-only get_contributions(Vec<Address>) -> Vec<i128> view.
• The new view preserves input order, mirrors get_contribution storage reads, returns 0 for unknown addresses, and rejects oversized batches with EscrowError::ContributionReadBatchTooLarge.
• Added funding tests for order preservation, unknown/duplicate addresses, empty input, exact cap, and over-cap typed error handling.
• Documented the new read API and error code.

CI unblock notes

• Ran cargo fmt -p liquifact_escrow because CI checks the whole escrow package and main currently contains rustfmt diffs.
• Removed duplicate trailing guard_status_eq / guard_status_in helper definitions and added missing operational-pause typed errors so whole-package clippy can compile this branch.
• Moved HorizonNotRaised to a non-conflicting code (204) to avoid the existing duplicate discriminant with LegalHoldBlocksPartialSettle.
• Derived tier event fields from a single expression instead of reassignment so clippy does not fail on immutable/unused assignment diagnostics.

Security notes

• No authorization is required because the entrypoint only reads existing contribution records.
• The function does not write storage, emit events, or bump TTL.
• The input vector is bounded at 50 entries to cap per-call persistent reads.
• Unknown addresses are handled with the same 0 default as get_contribution, so the view cannot panic on absent contribution storage.

Validation

• cargo fmt -p liquifact_escrow -- --check
• git diff --check
• Attempted cargo test -p liquifact_escrow get_contributions -- --nocapture, but this local machine has Cargo 1.84.0 and fails before compiling because base64ct v1.8.3 requires edition2024 / Cargo 1.85+.