feat(db): add webhook schema, migration, and repository (#391)

* feat(db): add webhook schema, migration, and repository

Add the database foundation for workspace webhooks:

- Add workspace_webhooks table with migration (webhook_event enum,
  URL, secret, event subscriptions, active flag)
- Add webhook repository with CRUD operations
- Add webhooks schema definition with relations
- Extend card and list repos to return board/list names for
  webhook payload context

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(db): remove unused webhook_event enum and fix migration timestamp

- Remove dead webhook_event pgEnum from schema (events column uses text)
- Remove CREATE TYPE statement from migration SQL
- Fix migration journal timestamp to be chronologically after the
  notifications migration (idx 25)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat(db): return boardPublicId from card and list repo queries

Add board publicId to getWorkspaceAndCardIdByCardPublicId and
getWorkspaceAndListIdByListPublicId return values, needed for
correct boardId in webhook payloads.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(db): add workspaceId index and document secret exposure

- Add index on workspaceId for efficient webhook lookups per workspace
- Add JSDoc comment on getActiveByWorkspaceId explaining that it
  returns secrets for server-side HMAC signing only and must never
  be exposed via client-facing endpoints

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* refactor(db): extract parseEvents helper in webhook repo

DRY up 6 repeated JSON.parse-and-cast calls into a single helper
function, addressing reviewer feedback on PR #391.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

packages/db/migrations/meta/_journal.json

@@ -190,6 +190,13 @@
       "when": 1770521594167,
       "tag": "20260208033314_AddAttachmentToActivity",
       "breakpoints": true
+    },
+    {
+      "idx": 27,
+      "version": "7",
+      "when": 1771192000000,
+      "tag": "20260129210000_AddWorkspaceWebhooks",
+      "breakpoints": true
     }
   ]
 }