test: cover factory edge cases

[ProtonsAndElectrons]

Summary

• Add default-running factory edge-case coverage for initialization, admin transfer, pool creation, get_pool, and pool_wasm_hash behavior from Add comprehensive test coverage for factory contract edge cases #20.
• Replace the ignored create_pool tests with a small deployable mock pool WASM so deployment paths run in normal cargo test.
• Assert typed factory errors, exact admin auth/event payloads, deterministic pool addresses, per-pool count increments, zero-rate storage, and get_pool TTL extension.
• Remove unwrap() use from factory test assertions.

Fixes #20

Validation

• cargo test -p factory (29 passed, 0 ignored; on Windows this required a local-only temporary farming-pool crate-type workaround for the existing x86_64-w64-mingw32 cdylib export ordinal linker issue; not committed)
• cargo fmt -p factory -- --check
• cargo check -p factory --lib
• git diff --check