src:  Make public fields in public structs private, with getters, returning idiomatic types instead of exposting optimized implementation details like ArrayVec and CompactString

src/client.rs:  Client::populate_episodes():  Use reserve_exact() on episodes, since that isn't actually reused anymore

src/client.rs:  Client::get_episodes_by_show():  Use populate_episodes() directly so we can actually reuse the allocations

src/client.rs:  Client::get_shows():  Use populate_episodes() directly so we can actually reuse the allocations

src/client.rs:  Move most of the business logic for get_episodes() into new populate_episodes(), which takes allocations as mutable arguments to reuse them

src/client.rs:  Client::get_episodes():  Use get_titles(), which uses the faster indexkv::Store::get_many(), but at the cost of us having to do a temporary allocation here

src/client.rs:  Client::get_shows():  Use get_titles(), which makes use of indekv::Store::get_many(), instead of just repeating calls to get_show()

benches/benchmark.rs:  client_benches():  Scope off the lookup_single_title_cached benchmark so its temp dir and client are dropped before any subsequent tests

Cargo.toml:  De-optimize release mode a bit; remove thin LTO to improve compile time, re-enable unwinding, and include light debug symbols.  We only use this for testing.

src/client.rs:  Eliminate temp allocation every time we check to see if a cache should be invalidated