feat: Vbat precision increment (follow-up from PR #161)

[coderabbitai]

Vbat Precision Increment

This issue tracks the continuance of the work begun in #161 (branch vbat_precision_increment), which is currently on hold due to merge conflicts with master and required updates to MSP and EmuConfigurator.

Background

PR #161 is a cherry-pick of betaflight/betaflight#7255 and increases the internal precision of vbat-related values (including vbat_comp). It also introduces getLegacyBatteryVoltage to maintain backward MSP compatibility.

Original Authors — must be credited in any future merge or re-implementation

• @fgiudice98 — original betaflight implementation (commits cherry-picked from Increased Vbat precision betaflight/betaflight#7255)
• @tylercorleone — EmuFlight port, conflict resolution, and additional precision work in PR Vbat precision increment #161

Work Required to Resolve

• Rebase / re-apply PR Vbat precision increment #161 onto current master (significant merge conflicts exist)
• MSP impact: The PR adds getLegacyBatteryVoltage() to preserve backward MSP compatibility. This function and any related MSP message changes must be verified and fully tested against all MSP consumers (e.g., OSD, telemetry, blackbox).
• EmuConfigurator impact: Voltage-related parameters (scale, range values) exposed via MSP will change precision/range. EmuConfigurator UI controls and their allowed ranges must be updated to reflect the new precision (e.g., vbat_comp_ref range 100–500, vbat_scale and related fields).
• Regression-test voltage compensation and battery monitoring on hardware.
• Update CLI parameter documentation / help text if ranges or units change.

References

• PR (on hold): Vbat precision increment #161
• Betaflight upstream: https://github.com/betaflight/betaflight/pull/7255/commits
• Discussion / on-hold context: Vbat precision increment #161 (comment)

Notes

Any future resolve or re-implementation of this feature must credit the original authors (@fgiudice98 and @tylercorleone) for the effort already completed.