The board annotator needs to count mines around each safe cell, including diagonal neighbors. Finish the annotation so corners, edges and mine cells follow the same board rules.
Build the implementation in C under /app, with /app/run.sh as its entry point. Read one JSON request from standard input and write one JSON result to standard output. Input is a nonempty rectangular list of nonempty strings using . and *. Return strings retaining mines as * and replacing each . with the number of mines among its eight neighboring cells. Reject ragged boards or other characters.
Reject inputs that violate an explicit validation rule with exit status 2, no standard output, and {"error":"invalid_input"} on standard error. For valid input, exit with status 0. Keep the implementation reusable for new inputs; it must work offline and must not depend on the example data being the only data it receives.
Repair or replace the unfinished /app/run.sh and add source files under /app. Malformed JSON must use the same invalid-input response. Do not read /tests or /oracle from the application.