Specifies UC-01 through UC-09: extending RigCapabilities with tx/tx_limit/
vfo_switch/filter_controls/signal_meter flags, RigFilterState struct,
SetBandwidth/SetFirTaps protocol commands, new HTTP endpoints, and
frontend visibility gating via applyCapabilities() in app.js.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>
