fix(PE-1451): correct MatchFiles usage in autozip.brs DoesFileExist

[evan-morgan]

📝 Description

DoesFileExist() in the autorun.zip example's autozip.brs always returned false, even when the target file existed, because it called MatchFiles(filePath$, filePath$) with the full file path as both arguments. Per the BrightSign MatchFiles(path, pattern_in) contract, the first argument must be a directory and the pattern must not contain a directory separator, otherwise it returns zero results. This broke the zip-exists and already-extracted checks that drive the whole extraction flow.

Issue: PE-1451

📋 List of Changes

• DoesFileExist() now splits the incoming path into its directory and filename parts and calls MatchFiles(dirPath$, fileName$) correctly.

🧪 Steps to Test

1. Build the autorun-zip-package example and place autorun.zip at the root of an SD card.
2. Boot a player (BrightSignOS 7.0.60+) with the card inserted.
3. Confirm the debugger log shows the zip is detected, extracted, and renamed to autorun.zip.done, and the player reboots into the extracted app instead of failing the DoesFileExist check.

Notes to the Reviewer

Root cause was confirmed against the BrightSign developer docs (Global Functions > MatchFiles) and against a debugger repro from a partner (Guillaume Proux) showing MatchFiles("SD:", "autorun.zip") succeeds while MatchFiles("SD:/autorun.zip", "SD:/autorun.zip") does not.

📸 Screenshots

N/A

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