Rate limiting and other minor updates (#25)

- Updated proxy server so that now you don't need export
`PROXY_BASE_URL` variable anymore (and we set the proxy in conformance
test script)
- Minor updates in the `devrev-snapin-template.plain`
- Update `docs/attachments-extraction.md` according to suggestions from
https://codeplain.slack.com/archives/C08KCS9A830/p1758790879392599
- Added a generic template for data extraction in file
`templates/data_extraction_acceptance_test.plain`, which should be
utilized in any data extraction-related functional requirement.

## Related issues
https://app.devrev.ai/devrev/works/ISS-161566

Author: tjazerzen

devrev-snapin-template.plain

@@ -11,10 +11,10 @@
   - Please note that EventContextIn and EventContextOut interfaces are deprecated.
 
 - The External Domain Metadata is a JSON object that describes the logical domain model of an external system. It defines the types of external record types, the relationships between those record types, and the metadata associated with each field, including the field’s data type, human-readable name, and other descriptive attributes.
-  - Note: Resource "attachments" should not be included in The External Domain Metadata JSON object even if the external system supports attachments. This is handled automatically by The Airdrop SDK Library.
+  - Note: Resource "attachments" *MUST NOT* be included in The External Domain Metadata JSON object even if the external system supports attachments. This is handled automatically by The Airdrop SDK Library.
 
 - The Initial Domain Mapping is a JSON object that defines how the logical domain model described by The External Domain Metadata maps to the target domain model in DevRev. It specifies the correspondence between each external record type and DevRev leaf type, as well as the mapping of individual fields, including transformation logic, value conversions, and any fixed or default values.
-  - Note: Resource "attachments" should not be included in The Initial Domain Mapping JSON object even if the external system supports attachments. This is handled automatically by The Airdrop SDK Library.
+  - Note: Resource "attachments" *MUST NOT* be included in The Initial Domain Mapping JSON object even if the external system supports attachments. This is handled automatically by The Airdrop SDK Library.
 
 - The External Sync Unit Item Count is a numeric field representing the total number of items (such as cards) contained within a given external sync unit. It is accessible as "item_count" field of the external sync unit.
 

docs/attachments-extraction.md

@@ -33,6 +33,7 @@ import {
 
 const getAttachmentStream = async ({
   item,
+  event,
 }: ExternalSystemAttachmentStreamingParams): Promise<ExternalSystemAttachmentStreamingResponse> => {
   // IMPORTANT: "url" is not necessarily deployed on the base URL of The API. It could also be an external URL (e.g. https://example.com/attachment.pdf, https://devrev.ai, ...)
   const { id, url } = item;
@@ -44,7 +45,7 @@ const getAttachmentStream = async ({
       responseType: 'stream',
       headers: {
         'Accept-Encoding': 'identity',
-        'Authorization': ... // TODO: Authorization if needed
+        'Authorization': ... // TODO: Authorization if needed. Credentials should be read from event["payload"]["connection_data"]["key"]
       },
     });