`DuckDBPyRelation.query()`: reusing a virtual table name silently changes the result of an existing relation

### What happens?

`rel.query(virtual_table_name, sql)` returns a lazy relation that re-resolves `virtual_table_name` through the connection's catalog on **every** execution. Registering the same name again from a different relation therefore changes what an already-constructed relation returns, with no error, even after that relation has been executed once.

### Why it matters

Wrong data rather than an error. For a library this rules out any fixed name, so we generate a unique random name per call, which then accumulates.

### What I would expect

One of:

1. the derived relation binds the virtual table once, at construction, so it is unaffected by later registrations; or
2. re-registering a name that a live relation depends on raises; or
3. if this is intended, a note on the [relational API docs](https://duckdb.org/docs/stable/clients/python/relational_api) saying that the name is resolved late and must not be reused.

### To Reproduce

import duckdb

con = duckdb.connect()
a = con.sql("select 1 as a")
b = con.sql("select 999 as a")

first = a.query("v", "select a from v")
print(first.fetchall()) # [(1,)]

second = b.query("v", "select a from v") # same name, unrelated relation
print(second.fetchall()) # [(999,)]

print(first.fetchall()) # [(999,)] <- silently changed

### OS:

Darwin, arm64

### DuckDB Package Version:

1.1.0, 1.2.2 and 1.5.5.

### Python Version:

3.12

### Full Name:

Francesco Bruzzesi

### Affiliation:

narwhals-dev

### What is the latest build you tested with? If possible, we recommend testing with the latest nightly build.

I have tested with a stable release

### Did you include all relevant data sets for reproducing the issue?

Not applicable - the reproduction does not require a data set

### Did you include all code required to reproduce the issue?

- [x] Yes, I have

### Did you include all relevant configuration to reproduce the issue?

- [x] Yes, I have

Inizia dal punto di ingresso DuckDBPyRelation.query() ed esegui la riproduzione Python fornita sulle versioni del pacchetto elencate. Traccia quando viene risolto il nome della tabella virtuale, quindi aggiungi un test di regressione per il comportamento scelto: una relazione esistente non deve cambiare silenziosamente dopo che il nome viene riutilizzato, oppure il contratto di risoluzione tardiva deve essere documentato nella documentazione dell’API relazionale.

Scritto dal modello di indicizzazione a partire dal testo della issue.