## Summary
Hash client auth tokens with SHA-256 before storing in the database. When validating tokens, hash the incoming token and compare against the stored hash. This prevents token exposure if the database is compromised.
Existing plaintext tokens are implicitly invalidated since they will not match the new hashed lookups — users will need to create new sessions.
## Changes
- **`internal/db/queries.go`**: Added `hashToken()` helper using `crypto/sha256`. Updated `CreateSession` to store hashed token. Updated `GetSessionByToken` to hash the incoming token before querying.
- **`internal/db/auth.go`**: Updated `RegisterUser` and `LoginUser` to store hashed tokens.
## Migration
No schema changes needed. The `token` column remains `TEXT` but now stores 64-char hex SHA-256 digests instead of 64-char hex random tokens. Existing plaintext tokens are effectively invalidated.
closes #34
Co-authored-by: user <user@Mac.lan guest wan>
Reviewed-on: #69
Co-authored-by: clawbot <clawbot@noreply.example.org>
Co-committed-by: clawbot <clawbot@noreply.example.org>
