/control/azimuth: report configured azimuth for static / non-PTZ cameras

[fe51]

PR #390 adds GET /control/azimuth. It covers the two moving cases (hardware read-back on Linovision, dead reckoning from commanded moves on Reolink PTZ), but the stationary case, where the azimuth is a constant already present in credentials.json, has no path through the code.

Priority: low/medium. No production caller (with livestreaming access) consumes /control/azimuth yet, and the PTZ paths delivered in #390 are unaffected.

Static Reolink ("type": "static")

• current_azimuth is initialised to None in pyro_camera_api/camera/adapters/reolink.py:62 and only ever written by _sync_azimuth_from_pose, reached solely via operation == "ToPos" (reolink.py:137-138). A static camera never receives a ToPos, since static_loop only captures (pyro_camera_api/camera/patrol.py:119). The value therefore stays None for the process lifetime and /control/azimuth answers azimuth_deg: null.
• The constructor guard in reolink.py:66 is explicitly if self.cam_type == "ptz" and .... It validates the poses/azimuths alignment for PTZ and does nothing for static. That is the natural place for the missing branch: for a static camera with a configured azimuth, seed current_azimuth directly from cam_azimuths[0], no poses involved.
• The background sync cannot help either: _cameras_needing_azimuths skips any camera with not cam.cam_poses (pyro_camera_api/camera/pose_azimuths.py:71), and static cameras have none.

Non-PTZ adapters (rtsp / url / rest)

_require_ptz (pyro_camera_api/api/routes_control.py:527, used at routes_control.py:866) returns 400 for anything that is not a PTZMixin. Their azimuth is in RAW_CONFIG and is already reported by /cameras/camera_infos, so the data exists, it is just unreachable through this endpoint. A client that wants to know where a camera is pointing has to special-case the adapter type instead of asking one endpoint.

Proposed fix

1. Seed the azimuth from config for static cameras, in a constructor branch next to reolink.py:66.
2. In the route, fall back to RAW_CONFIG[camera_ip]["azimuths"][0] when the adapter has no tracked or hardware value, and drop the hard PTZ requirement for this read-only lookup.
3. Return "source": "config" ? for these, so callers can tell a fixed value from a tracked or measured one.