Stability fixes: streaming, comms, chip drivers, boards, CLI (batch 8)

[dmitrymmm]

A full-codebase audit pass. 32 fixes, one defect per commit, each verified by
reading the code path; no behavioural change intended beyond correcting the defect.
Builds clean and the unit test suite (59 tests) passes. The Windows-only USB fixes,
the board/PCIe fixes and the RF-configuration fixes still want a bench check, but the
defects are all visible from the code.

comms

• FT601 (Windows): AbortXfer no longer releases the OVERLAPPED that the following
  WaitForXfer/FinishDataXfer still use, and BeginDataXfer stops leaking the event
  handle it created twice per transfer.
• FX3 (Windows): BulkTransfer returns the actual transferred count, so short transfers
  are visible to callers instead of looking complete.
• USBDMAEmulation: transfers that complete short or errored are reported instead of
  being counted as full buffers and parsed as stale samples.
• PCIe: RunControlCommand bounds the caller length to the 64-byte ioctl packet.

streaming

• Rx UNIX_EPOCH timestamps: the epoch/front-end-delay correction is applied once per
  user packet instead of once per batched hardware packet.
• Tx: null meta and asymmetric channel configs (more Rx than Tx channels) no longer
  dereference or memcpy from a null pointer.
• StreamComposite: sample-tick Tx timestamps keep their tick rate instead of being
  divided by the sample rate twice.
• The packet pool is clamped so a low/absent sample-rate hint cannot underflow the FIFO
  size to SIZE_MAX.

protocols

• Custom parameter scaling guards log10 of non-positive values and masks the exponent
  nibble.
• WriteSerialNumber and SPI_generic no longer build outgoing packets on top of the
  bytes the device wrote back into the shared buffer.

chip drivers

• LMS7002M: channel B config load reads the ch.B NCO section, IsSynced selects MAC B
  before the readback, and the MCU-assisted write verifies against the chip not the
  cache.
• embedded lms7002m: VDIV_VCO restored to 0xB9 (not 0xFF), RSSI settling delay
  saturates instead of truncating to 16 bits, the CGEN divider midpoint is clamped
  rather than masked, the calibration save/restore buffers are per-context, and the
  batch flush masks the upper MISO half.
• CDCM6208: fractional divider no longer wraps its 8-bit integer part, the read-back
  loop stops before the phantom map entry at address 0, and the input-mux recompute
  conditions are corrected.
• Si5351C: PLL denominator registers are assigned (not OR'd over defaults) and PLLB
  uses its own input frequency.
• ADF4002: R/N counters are validated against their 14/13-bit fields before packing.

boards

• LimeSDR-X3: the LMS3 RF switch bit is computed from the per-chip channel instead of a
  negative shift.
• MMX8: the stream data path is routed through the module's own streamers with null
  guards, and StreamSetup fails when a subdevice stream cannot be created.
• The Tx test signal is configured even when the Rx test signal is enabled.
• LimeSDR-XTRX: the GNSS UART test terminates on a read timeout instead of spinning.

FPGA / DSP

• SetInterfaceFreq fails on a failed LMS7002M readback instead of using uninitialized
  values, and skips bypassed/zero-frequency clocks so the divider math cannot divide by
  zero.
• FFT window coefficients are swapped under a mutex and read under it on the worker
  thread; the average count is atomic.
• CFR derives the FIR odd flag from the actual tap count.

legacyapi / CLI

• LMS_RecvStream reports the Rx timestamp, LMS_DestroyStream tears the shared stream
  down only when no channels remain and matches the align-phase-masked index,
  LMS_Read/WriteParam preserve the current MAC selection, and the NCO frequency
  functions guard a null table pointer.
• LimePlugin validates max_channels_to_use and releases the calibration stream before
  the devices it references are freed.
• limeTRX resends the tail of a partial Tx and checks the output file; limeConfig
  resolves a relative --ini against the CWD and frees the device on error; limePPSDO
  selects the register map from the connected device and returns a failure exit code;
  frontendDelayTest checks the StreamCreate result.