Add document approval workflow

Introduce a complete approval system for document publishing. Document
versions can now require approval from selected reviewers before being
published, with automatic publishing once all approvers have approved.

- Add approval quorum and decision tables with backfill migration
- Implement request approval, approve, and reject flows with electronic
  signature support for approve decisions
- Add employee approvals page with dedicated tab and pending approvals view
- Add changelog field to publish and request approval flows
- Pre-select previous version's approvers in the publish dialog
- Show quorum approvers in document list with 100 approver hard limit
- Expose approval workflow through GraphQL, MCP, and CLI
- Remove legacy default approvers feature entirely
- Add comprehensive e2e test coverage for approval workflows

Signed-off-by: Sacha Al Himdani <sacha@getprobo.com>

pkg/server/api/mcp/v1/specification.yaml

@@ -5184,7 +5184,6 @@ components:
       required:
         - id
         - organization_id
-        - approver_ids
         - title
         - document_type
         - classification
@@ -5199,11 +5198,6 @@ components:
         organization_id:
           $ref: "#/components/schemas/GID"
           description: Organization ID
-        approver_ids:
-          type: array
-          items:
-            $ref: "#/components/schemas/GID"
-          description: Approver IDs
         title:
           type: string
           description: Document title
@@ -5246,7 +5240,6 @@ components:
         - organization_id
         - document_id
         - title
-        - approver_ids
         - version_number
         - classification
         - content
@@ -5267,11 +5260,6 @@ components:
         title:
           type: string
           description: Document version title
-        approver_ids:
-          type: array
-          items:
-            $ref: "#/components/schemas/GID"
-          description: Approver IDs
         version_number:
           type: integer
           description: Version number
@@ -5418,7 +5406,6 @@ components:
         - organization_id
         - title
         - content
-        - approver_ids
         - classification
         - document_type
       properties:
@@ -5431,11 +5418,6 @@ components:
         content:
           type: string
           description: Document content
-        approver_ids:
-          type: array
-          items:
-            $ref: "#/components/schemas/GID"
-          description: Approver IDs
         classification:
           $ref: "#/components/schemas/DocumentClassification"
           description: Document classification
@@ -5468,11 +5450,6 @@ components:
         title:
           type: string
           description: Document title
-        approver_ids:
-          type: array
-          items:
-            $ref: "#/components/schemas/GID"
-          description: Approver IDs
         classification:
           $ref: "#/components/schemas/DocumentClassification"
           description: Document classification
@@ -5639,7 +5616,7 @@ components:
           description: Document ID
         changelog:
           type: string
-          description: Changelog
+          description: Changelog for this version
 
     PublishDocumentVersionOutput:
       type: object
@@ -5652,6 +5629,32 @@ components:
         document_version:
           $ref: "#/components/schemas/DocumentVersion"
 
+    RequestDocumentVersionApprovalInput:
+      type: object
+      required:
+        - document_id
+        - approver_ids
+      properties:
+        document_id:
+          $ref: "#/components/schemas/GID"
+          description: Document ID
+        approver_ids:
+          type: array
+          items:
+            $ref: "#/components/schemas/GID"
+          description: Approver profile IDs
+        changelog:
+          type: string
+          description: Changelog for this version
+
+    RequestDocumentVersionApprovalOutput:
+      type: object
+      required:
+        - document_version
+      properties:
+        document_version:
+          $ref: "#/components/schemas/DocumentVersion"
+
     DeleteDocumentInput:
       type: object
       required:
@@ -7476,6 +7479,14 @@ tools:
       $ref: "#/components/schemas/PublishDocumentVersionInput"
     outputSchema:
       $ref: "#/components/schemas/PublishDocumentVersionOutput"
+  - name: requestDocumentVersionApproval
+    description: Request approval for a document version
+    hints:
+      readonly: false
+    inputSchema:
+      $ref: "#/components/schemas/RequestDocumentVersionApprovalInput"
+    outputSchema:
+      $ref: "#/components/schemas/RequestDocumentVersionApprovalOutput"
   - name: deleteDocument
     description: Delete a document
     hints: