[Bug]: Auto-allocated measurement names make conditionals unparseable under the canonical grammar

[fedonman]

Bug Description

A measurement on a schema-backed bus with no explicit name= gets an auto-name that embeds the bus path, q0/readout/m0, because _measurement_name_prefix joins with a slash. The writer's _MEASUREMENT_REF_UNSAFE pattern does not list / as unsafe, so a conditional on that handle goes out unquoted as if q0/readout/m0.state == 1:. The production parser reads it back fine, but qp.lark's DOTTED_NAME terminal only admits identifier characters, so the reference parser lexes the slash as BIN_OP and fails. The default path therefore produces a file the normative grammar rejects; either give the auto-name a token-safe separator or widen the grammar's handle terminal.

Minimal Reproducible Example

import qprogram as qp
from qprogram.buses import BusSchema
from qprogram.grammar import parse_text

s = BusSchema.transmon()
p = qp.QProgram(schema=s)
m = p.measure(s.q[0].readout, "readout", "weights")
with p.if_(m.state == 1):
    p.wait(s.q[0].drive, 100)
parse_text(qp.dumps(p))

Expected Behavior

Writer output parses under the canonical grammar, which is what tests/test_grammar.py exists to keep true.

Actual Behavior

lark.exceptions.UnexpectedToken: Unexpected token Token('BIN_OP', '/') at line 10, column 8.
Expected one of: 
	* CMP_OP

.qp Text

body:
  measure q[0].readout "readout" "weights" name="q0/readout/m0"
  if q0/readout/m0.state == 1:
    wait q[0].drive 100

System Information

qprogram 0.1.0
python   3.14.3 | Linux-7.0.0-30-generic-x86_64-with-glibc2.43
vendors  none