Replace the inline copy of the Argon2id PHC dummy hash in
crates/manager-core/src/auth_api.rs::login with a reference to the
shared TIMING_FLAT_DUMMY_HASH constant in
crates/manager-core/src/auth.rs (added in v1.1.8 but not yet adopted
by the login path).
Verification: `grep -rn 'argon2id\$v=19\$m=19456,t=2,p=1\$dGltaW5n' crates/`
returns exactly one hit — the const declaration in auth.rs.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
0c85fb67d3