feat: add .zip document support and auto-mount cache dirs into remote backends (#4846)

- Add .zip to SUPPORTED_DOCUMENT_TYPES so gateway platforms (Telegram,
  Slack, Discord) cache uploaded zip files instead of rejecting them.
- Add get_cache_directory_mounts() and iter_cache_files() to
  credential_files.py for host-side cache directory passthrough
  (documents, images, audio, screenshots).
- Docker: bind-mount cache dirs read-only alongside credentials/skills.
  Changes are live (bind mount semantics).
- Modal: mount cache files at sandbox creation + resync before each
  command via _sync_files() with mtime+size change detection.
- Handles backward-compat with legacy dir names (document_cache,
  image_cache, audio_cache, browser_screenshots) via get_hermes_dir().
- Container paths always use the new cache/<subdir> layout regardless
  of host layout.

This replaces the need for a dedicated extract_archive tool (PR #4819)
— the agent can now use standard terminal commands (unzip, tar) on
uploaded files inside remote containers.

Closes: related to PR #4819 by kshitijk4poor

tools/environments/docker.py

@@ -315,7 +315,11 @@ class DockerEnvironment(BaseEnvironment):
         # Mount credential files (OAuth tokens, etc.) declared by skills.
         # Read-only so the container can authenticate but not modify host creds.
         try:
-            from tools.credential_files import get_credential_file_mounts, get_skills_directory_mount
+            from tools.credential_files import (
+                get_credential_file_mounts,
+                get_skills_directory_mount,
+                get_cache_directory_mounts,
+            )
 
             for mount_entry in get_credential_file_mounts():
                 volume_args.extend([
@@ -341,6 +345,21 @@ class DockerEnvironment(BaseEnvironment):
                     skills_mount["host_path"],
                     skills_mount["container_path"],
                 )
+
+            # Mount host-side cache directories (documents, images, audio,
+            # screenshots) so the agent can access uploaded files and other
+            # cached media from inside the container.  Read-only — the
+            # container reads these but the host gateway manages writes.
+            for cache_mount in get_cache_directory_mounts():
+                volume_args.extend([
+                    "-v",
+                    f"{cache_mount['host_path']}:{cache_mount['container_path']}:ro",
+                ])
+                logger.info(
+                    "Docker: mounting cache dir %s -> %s",
+                    cache_mount["host_path"],
+                    cache_mount["container_path"],
+                )
         except Exception as e:
             logger.debug("Docker: could not load credential file mounts: %s", e)