index_videos.py calls sys.exit() at import time on missing deps

[niranjans]

What

The dependency check at the top of src/framedex/index_videos.py runs at module import time and calls sys.exit(1) on a missing dependency:

try:
    import requests
    import whisperx
    import yaml
except ImportError as e:
    print(f"Missing dependency: {e}", file=sys.stderr)
    print("Run: uv pip install -e .", file=sys.stderr)
    sys.exit(1)

Because this sits at module top level, it fires the instant anything does import framedex.index_videos — including from framedex.index_videos import some_function.

Why it's a problem

• A module shouldn't terminate the process. A failed import should raise ImportError and let the caller decide. Here the module unilaterally kills the whole program — that's the application's call, not a library file's.
• The module can't be imported without the full heavy stack. Reusing or testing a single function from index_videos.py requires whisperx (→ torch, multi-GB) to be installed, even for code paths that never touch it.
• It already forced a workaround. The pure helpers were extracted into framedex/parsing.py specifically so they could be unit-tested without tripping this sys.exit. The root wart still lives in index_videos.py.
• Now that people are forking and building on framedex, anyone with a partial install or library use case hits an abrupt process exit instead of a clean, catchable error.

Proposed fix

Move the dependency check off module top level. Either:

• Lazy import — import whisperx etc. inside the functions that use them. Importing the module becomes cheap and safe.
• Or check inside main() — exiting the process from the CLI entry point is legitimate, because there you are the process.

CLI behavior is unchanged: running fdx with deps missing still prints the same clear error. It just stops being hostile to plain imports.

Severity

Real, not urgent — the CLI works fine today. Worth a clean fix in its own PR. Happy to take this if no one's on it.