fix(quickadapter): avoid duplicate backtest exit reserve (#152)

fix(quickadapter): avoid duplicate backtest exit reserve (#152)

The partial-exit minimum bound previously multiplied `min_stake` by the
stoploss/rate factor `max(current_exit_rate/current_entry_rate,
1/(1-|stoploss|))` in every runmode. In backtest/hyperopt, Freqtrade already
passes the adjusted minimum it guards the remainder against, so that factor
duplicated the stoploss reserve. Apply the factor only in live/dry-run
(is_trade_runmode == TRADE_MODES = {LIVE, DRY_RUN}), where the callback supplies
min_entry_stake (stoploss 0.0) but the guard uses the larger min_exit_stake;
keep the 0.1% numerical clearance in both modes. Live/dry-run behavior is
bit-for-bit unchanged. Freqtrade remains responsible for amount precision and
final pre-order minimum validation.

Also rename the local bound to `min_remaining_position_value` (it is the minimum
acceptable remaining position value, not an exit stake).

Fixes #138