fix(Patch): recover from interrupted patch instead of failing as corrupted

After a cancelled patch attempt, some files in installPath may already
be at the target version while the krpdiff expects old-version sources.
This causes ApplyDirPatch to crash or produce incorrect output.

Three layers of defense:

1. Delete pre-flight state file before Step 8 - forces fresh pre-flight
   on retry so already-updated files are correctly detected.

2. Source file size pre-check - extends the existing missing-file check
   to also verify source file sizes match the krpdiff expectation.
   Wrong-size files (from previous partial move) skip the doomed patch
   and go straight to CDN download. No more waiting for SharpHDiffPatch
   to read multi-GB files and crash.

3. CDN fallback on patch failure - when ApplyDirPatch crashes (integer
   overflow, array bounds, etc.) or post-patch MD5 mismatches, each
   destination file is checked: if already at target, skip; otherwise
   download from CDN. Replaces the hard throw that reported corruption.

4. Clean up leftover temp dirs before re-patching to avoid stale output
   from a previous interrupted verify+move loop.

Author: Cryotechnic