Add a maximum output FPS limit feature

[chyanbo]

1. Fixed the frame loss issue at the end of videos in previous versions.
2. Fixed the issue where the playback FPS setting affected recording.
3. Added a maximum output FPS limit feature. When enabled, videos with FPS higher than the set value will be processed and output using the specified FPS.
4. Other small bug fixes.

[Copilot]

Pull request overview

This PR updates the video processing/recording pipeline to (a) decouple playback FPS overrides from recording output FPS, (b) address end-of-video frame-loss behavior, and (c) add a new “maximum output FPS” cap for recording via an FFmpeg-driven input path.

Changes:

• Adds new recording settings to enable/disable an output FPS cap and configure the maximum FPS.
• Updates UI time/slider behavior to stay in source-frame space while recording with FPS-cap enabled.
• Extends audio segment extraction and recording finalization logic to better align audio timings when frame sampling/FPS-capping is involved.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

File	Description
app/ui/widgets/settings_layout_data.py	Adds UI settings for enabling and configuring the maximum output FPS cap; clarifies playback-FPS help text.
app/ui/widgets/actions/video_control_actions.py	Adjusts timeline time calculation to use source FPS when FPS-cap recording is active.
app/processors/video_utils/video_encoding.py	Extends extract_audio_segments to support frame-origin/time offsets for correct segment timing.
app/processors/video_processor.py	Implements FFmpeg FPS-cap input path, tail-drain logic for recording finalization, and source/output frame mapping utilities.

Comments suppressed due to low confidence (1)

app/processors/video_processor.py:4261

• This comment contains garbled characters ("output frame �?source frame"), likely due to an encoding issue. Please replace with a plain ASCII/Unicode arrow (e.g., "output frame -> source frame") so the source file remains clean and readable.

                # If FPS-cap recording was active, map output frame �?source frame before seek.