op25: pin gr310 to 5b58335; analog defaults to OP25 noise squelch (node-26#46, node-26#29)

- op25-container/Dockerfile: clone gr310 then check out 5b58335 (OP25_COMMIT
  build arg). That is the gr310 merge tk_drb_conv was verified against for
  #29 and the first carrying PR #296's NBFM noise/voice squelch. Changing
  the RUN line also busts CI's cached unpinned clone.
- Keys verified from op25_nbfm.py at that commit: nbfm_squelch_mode
  (power|noise|voice), nbfm_noise_squelch_db, nbfm_squelch_threshold, read
  from the channel dict.
- op25-container: ConfigGenerator.nbfm_squelch_mode (enum, default noise) and
  nbfm_noise_squelch_db, written onto the analog channel.
- edge-node: system config squelch_mode / squelch_db / squelch_threshold ->
  generate payload (validated, noise when absent); /api/listen and the
  dashboard's analog pane expose mode and level.

#29's CI test of tk_drb_conv against the real tk_p25.py is not done here.

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

op25-container/app/routers/op25_controller.py

@@ -262,6 +262,8 @@ def create_op25_router():
                     frequency=freq,
                     meta_stream_name="",
                     nbfm_squelch_threshold=generator.nbfm_squelch,
+                    nbfm_squelch_mode=generator.nbfm_squelch_mode.value,
+                    nbfm_noise_squelch_db=generator.nbfm_noise_squelch_db,
                 )]
                 devices = [DeviceConfig(
                     gains=preset["gains"], ppm=ppm, tunable=False,