refactor: rename nssa/nssa_core → lee/lee_core

Follow the spel fork's `nssa → lee` refactor (chore/update-lez): the
`#[lez_program]` macro now emits `lee_core::…` paths, so the crate must be
referenced by its real name rather than the `nssa_core` alias.

- Cargo.toml: rename the `nssa_core`/`nssa` dep keys to `lee_core`/`lee` and
  drop the now-redundant `package = "lee_core"`/`package = "lee"` aliases
  (dep name == package name).
- Rust: `nssa_core::` → `lee_core::`, `nssa::` → `lee::` across programs,
  modules, and tools.
- Docs: update the library reference in CLAUDE.md and README.md.

Also drop the dead `NSSA_WALLET_HOME_DIR` env var — superseded by
`LEE_WALLET_HOME_DIR`, which is the only wallet-home var any v0.2.x wallet
reads — from the test tooling (setup-amm-testnet.sh, custom-token.mjs,
run-basecamp-e2e.sh) and docs.

Closes #225

programs/integration_tests/tests/token.rs

@@ -1,11 +1,11 @@
-use nssa::{
+use lee::{
     execute_and_prove,
     privacy_preserving_transaction::{Message, PrivacyPreservingTransaction, WitnessSet},
     program::Program,
     program_deployment_transaction::{self, ProgramDeploymentTransaction},
     public_transaction, PrivateKey, PublicKey, PublicTransaction, V03State,
 };
-use nssa_core::{
+use lee_core::{
     account::{Account, AccountId, AccountWithMetadata, Data, Nonce},
     encryption::ViewingPublicKey,
     Commitment, InputAccountIdentity, NullifierPublicKey, NullifierSecretKey,
@@ -35,11 +35,11 @@ impl Keys {
 }
 
 impl Ids {
-    fn token_program() -> nssa_core::program::ProgramId {
+    fn token_program() -> lee_core::program::ProgramId {
         token_methods::TOKEN_ID
     }
 
-    fn foreign_token_program() -> nssa_core::program::ProgramId {
+    fn foreign_token_program() -> lee_core::program::ProgramId {
         [0xfeed_u32; 8]
     }