- isNamedLinearTransponder: match ' Lin' prefix (AO-7 style) and
add fallback branch (hasLinearName && hasLinearMode) for entries
with 'Linear'/'Lin' but no 'transponder' word (AO-7, AO-73)
- add deduplicateTransponders: merge entries sharing the same
uplink/downlink frequency range, preferring non-CW entry
(AO-7 Mode A had separate SSB and CW entries; JO-97 had
separate CW and SSB Transponder entries)
- apply dedup in CalculatorPage filter chain
- 6 new tests, 23 total, all passing
