Implement configurable EXIF stripping for uploaded media

- Add `strip_exif` configuration option to enable metadata removal.
- Add `mogrify_path` configuration to specify external tool location.
- Implement strip_media using `mogrify -strip`.
- Support multiple image formats: jpg, png, webp, heic, heif, avif, tiff, gif, bmp.
- Add strict startup check: fail to start if `strip_exif` is enabled but `mogrify` is missing/broken.
- Update documentation in `doc/snac.8`.

1 files changed, 3 insertions, 0 deletions

diff --git a/snac.h b/snac.h
index 8a7dad6..c307dbd 100644
--- a/snac.h
+++ b/snac.h
@@ -105,6 +105,9 @@ int validate_uid(const char *uid);
 xs_str *hash_password(const char *uid, const char *passwd, const char *nonce);
 int check_password(const char *uid, const char *passwd, const char *hash);
 
+int strip_media(const char *fn);
+int check_strip_tool(void);
+
 void srv_archive(const char *direction, const char *url, xs_dict *req,
                  const char *payload, int p_size,
                  int status, xs_dict *headers,