feat(storage): namespace storage keys across contract modules (#1055)

[Killerjunior]

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feat(storage): namespace storage keys across contract modules

Closes #1055

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Summary

This PR implements a type-safe, production-ready storage key namespacing framework across the entire Callora workspace, resolving [Quality-2][High] Namespace storage keys across contract modules.

Prior to this change, storage keys used by individual contracts had no structural namespace, no explicit ownership semantics, inconsistent TTL/archival policies, and no protection against cross-module state collision. This PR addresses all of that systematically.

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Changes

contracts/helpers — Core Framework

• ContractNamespace — #[contracttype] enum covering all workspace contract modules. Each variant uniquely scopes every key written by that module.
• KeyCategory — Structural classification (Config, State, Accounting, Ephemeral, Idempotency, Migration) with explicit durability mapping (Instance/Persistent/Temporary) and TTL parameters per category.
• NamespacedKey<K> — Composite tuple key (ContractNamespace, KeyCategory, K) with manual Soroban IntoVal/TryFromVal serialization that is compatible with #[contracttype] restrictions on generic types.
• KeyOwnershipMarker — Audit trail record capturing namespace, category, optional owner address, creation ledger sequence, and lifecycle timestamps (migration, archival).
• NamespacedStorage<'a> — Safe storage engine providing instance_*, persistent_*, and temporary_* operations with:
  • Automatic TTL extension on hot reads
  • Explicit idempotency pruning and migration cleanup
  • Multi-tenant isolation guardrails via debug assertions on cross-namespace key access
  • bulk_instance_bump for contract liveness management

All 28 Workspace Contract Crates

• Added callora-helpers as a dependency in each contract's Cargo.toml
• Exposed a standardized pub mod ns in each contract's src/lib.rs binding:
  • CONTRACT_NS: ContractNamespace — the module-level namespace discriminant
  • storage(env: &Env) -> NamespacedStorage<'_> — zero-overhead namespace-bound accessor
  • Re-exports of all key construction helpers (config_key, state_key, accounting_key, ephemeral_key, idempotency_key, migration_key)

contracts/tests — Integration Test Suite

Added namespaced_storage.rs to callora-cross-contract-tests with four test cases:

Test	Coverage
test_namespaced_storage_lifecycle_and_isolation	Fresh writes, hot reads, expiry/cleanup, recovery — all 6 key categories
test_ownership_marker_audit_trail	Marker field correctness, describe() output
integrated_contracts_expose_own_namespace	All 28 contracts bind the correct CONTRACT_NS
integrated_storage_accessors_bind_matching_namespace	All 28 storage(&env) return the correct namespace

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Test Results

cargo test --package callora-helpers --package callora-cross-contract-tests

callora-cross-contract-tests: 11 passed; 0 failed
callora-helpers:              22 passed; 0 failed

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CI Checklist

• cargo fmt --all -- --check — clean
• cargo clippy --package callora-helpers --package callora-cross-contract-tests -- -D warnings — clean
• All 33 tests pass locally (22 unit + 11 integration)
• No breaking changes to existing public contract APIs
• All pub mod ns bindings are additive — no existing code paths touched

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[Killerjunior]

Kindly review and merge @greatest0fallt1me