feat(vet): allow vet to lint anonymous parameter names

[JasonDav]

Allow vet to check for empty Parameter names

sqlc vet lets you write CEL lint rules against your queries, but today the only information exposed about a query parameter is its position (number):

message Parameter {
  int32 number = 1;
}

That makes it impossible to write a rule about anonymous parameters — parameters sqlc couldn't derive a name for, which it renders in generated code with names Column1, Column2, etc in the golang output.
Anonymous parameters mean ugly and borderline unreadable for large queries hence large param lists.
In this case we force engineers to go back and name them so that the Param structs properties are readable.
Catching them today requires a manual review pass; there's no way to fail sqlc vet on them.

This PR exposes the parameter's name to vet rules so you can lint for this yourself.

What this enables

# sqlc.yaml
rules:
  - name: no-anonymous-params
    message: "don't use anonymous parameters"
    rule: |
      query.params.exists(p, p.name == "")

Given a query whose parameter sqlc can't name:

-- name: ListByIDs :many
SELECT id FROM authors WHERE id = ANY($1::bigint[]);

sqlc vet now fails:

$ sqlc vet
query.sql: ListByIDs: no-anonymous-params: don't use anonymous parameters
# exit status 1

Naming the parameter clears it:

-- name: ListByIDs :many
SELECT id FROM authors WHERE id = ANY(sqlc.arg(ids)::bigint[]);   -- or @ids

$ sqlc vet
# exit status 0

Backward compatibility

Purely additive. name is a new optional proto field; existing vet rules and configs are unaffected, and the field defaults to "" for any parameter without a column.

Test plan

• go build ./...
• go test ./internal/endtoend/ -run 'TestReplay/.*/vet_' — passes (all vet replay cases, both new cases on base and managed-db)
• Verified end-to-end against a built binary: anonymous param → vet exits 1 with the violation; named param → exits 0.