HEALTH_DIAG `sigma_mag` / `sigma_dir` were reporting raw weight_sigma
mean (constant 0.0320 across schedules) because reset_noise_with_sigma
only scaled the noise epsilon samples, not the underlying σ tensor.
Fix: added current_sigma_scale: f32 field on NoisyLinear (default 1.0),
updated in reset_noise_with_sigma, multiplied through in sigma_mean()
accessor. Also propagated through copy_params_from so target-net sync
does not reset the reported effective σ.
The HEALTH_DIAG field now reflects the scheduled effective σ, enabling
H7 detection signal to actually observe schedule attenuation.
Closes Track 4 E2 TUNE finding from Phase 1 triage.
ef165e8961