feat(auth): sessions expire server-side; password change and reset end other sessions (M462 #4978)

Sessions had no server-side expiry: only the web cookie's 30-day Max-Age
limited them, and a bearer token (Android) lived until revoked by hand.
GetSessionByTokenHash and ListSessionsForUser now ignore sessions idle for
30 days or older than a year, and the GC worker deletes them hourly.

A password change was a plain UPDATE, so a session opened with the old
password survived it. Now:
- self-service change signs out every other device and keeps this one;
- reset by email ends every session the account has;
- an admin reset ends the target's sessions (keeping the admin's own when
  they reset themselves).

The success copy on web and Android says the other devices were signed out.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/db/dbq/sessions.sql.go

@@ -69,10 +69,38 @@ func (q *Queries) DeleteSessionForUser(ctx context.Context, arg DeleteSessionFor
 	return result.RowsAffected(), nil
 }
 
-const getSessionByTokenHash = `-- name: GetSessionByTokenHash :one
-SELECT id, user_id, token_hash, user_agent, created_at, last_seen_at, created_ip, last_ip FROM sessions WHERE token_hash = $1
+const deleteSessionsForUser = `-- name: DeleteSessionsForUser :execrows
+DELETE FROM sessions WHERE user_id = $1
 `
 
+// Every session the user has, the caller's included. A password reset uses
+// it: whoever forgot the password is not signed in anywhere they trust, and
+// whoever may have learned it must be signed out everywhere.
+func (q *Queries) DeleteSessionsForUser(ctx context.Context, userID pgtype.UUID) (int64, error) {
+	result, err := q.db.Exec(ctx, deleteSessionsForUser, userID)
+	if err != nil {
+		return 0, err
+	}
+	return result.RowsAffected(), nil
+}
+
+const getSessionByTokenHash = `-- name: GetSessionByTokenHash :one
+SELECT id, user_id, token_hash, user_agent, created_at, last_seen_at, created_ip, last_ip FROM sessions
+WHERE token_hash = $1
+  AND last_seen_at > now() - interval '30 days'
+  AND created_at > now() - interval '365 days'
+`
+
+// Expired sessions are invisible here, so they fail auth the moment they
+// lapse rather than whenever the GC sweep next runs. Two limits:
+//
+//	idle 30 days     — a token nobody has used in a month is abandoned, and
+//	                   matches the web cookie's lifetime;
+//	absolute 1 year  — even a token in daily use is re-issued yearly, so a
+//	                   stolen one that is being used quietly does not live
+//	                   forever.
+//
+// Keep in step with ListSessionsForUser and GcDeleteExpiredSessions.
 func (q *Queries) GetSessionByTokenHash(ctx context.Context, tokenHash []byte) (Session, error) {
 	row := q.db.QueryRow(ctx, getSessionByTokenHash, tokenHash)
 	var i Session
@@ -127,11 +155,17 @@ func (q *Queries) InsertSession(ctx context.Context, arg InsertSessionParams) (S
 }
 
 const listSessionsForUser = `-- name: ListSessionsForUser :many
-SELECT id, user_id, token_hash, user_agent, created_at, last_seen_at, created_ip, last_ip FROM sessions WHERE user_id = $1 ORDER BY last_seen_at DESC
+SELECT id, user_id, token_hash, user_agent, created_at, last_seen_at, created_ip, last_ip FROM sessions
+WHERE user_id = $1
+  AND last_seen_at > now() - interval '30 days'
+  AND created_at > now() - interval '365 days'
+ORDER BY last_seen_at DESC
 `
 
 // Most-recently-active first: the row a user is most likely to act on is the
 // one that moved last, and an unfamiliar entry at the top is the alarm.
+// Expired rows are left out: they no longer authenticate, so listing them
+// as active would be wrong. Same limits as GetSessionByTokenHash.
 func (q *Queries) ListSessionsForUser(ctx context.Context, userID pgtype.UUID) ([]Session, error) {
 	rows, err := q.db.Query(ctx, listSessionsForUser, userID)
 	if err != nil {