Add AI-powered evidence description generation

Introduce a background worker that automatically generates
compliance-focused descriptions for uploaded evidence files
using configurable LLM providers. Descriptions are surfaced
across all interfaces: GraphQL API, MCP API, CLI, and the
console UI.

Key changes:
- Multi-provider LLM config with per-agent settings (pointer
  types for Temperature/MaxTokens to preserve zero values)
- Evidence description worker with bounded concurrency
- EvidenceDescriptionStatus typed enum with PostgreSQL enum type
- New `prb evidence` CLI commands (list, view, delete)
- Evidence description displayed in console table and preview
- Migration only marks evidences without files as completed

Signed-off-by: Bryan Frimin <bryan@getprobo.com>

apps/console/src/hooks/graph/EvidenceGraph.ts

@@ -7,6 +7,7 @@ export const evidenceFileQuery = graphql`
     node(id: $evidenceId) {
       ... on Evidence {
         id
+        description
         file {
             mimeType
             fileName

apps/console/src/pages/organizations/measures/dialog/EvidencePreviewDialog.tsx

@@ -125,39 +125,48 @@ function EvidencePreviewContent({
     );
   }
 
+  let preview;
+
   if (evidence.file.mimeType?.startsWith("image/")) {
-    return (
+    preview = (
       <img
         src={evidence.file.downloadUrl}
         alt={evidence.file.fileName}
         className="max-h-[70vh] object-contain"
       />
     );
-  }
-
-  if (evidence.file.mimeType?.includes("pdf")) {
-    return (
+  } else if (evidence.file.mimeType?.includes("pdf")) {
+    preview = (
       <iframe
         src={evidence.file.downloadUrl}
         className="w-full h-[70vh]"
         title={evidence.file.fileName}
       />
     );
+  } else {
+    preview = (
+      <div className="flex flex-col items-center gap-2 justify-center">
+        <IconWarning size={20} />
+        <p className="text-txt-secondary text-center">
+          {__("Preview not available for this file type")
+            + " "
+            + evidence.file.mimeType}
+        </p>
+        <Button asChild variant="secondary" icon={IconArrowInbox}>
+          <a href={evidence.file.downloadUrl} target="_blank" rel="noreferrer">
+            {__("Download File")}
+          </a>
+        </Button>
+      </div>
+    );
   }
 
   return (
-    <div className="flex flex-col items-center gap-2 justify-center">
-      <IconWarning size={20} />
-      <p className="text-txt-secondary text-center">
-        {__("Preview not available for this file type")
-          + " "
-          + evidence.file.mimeType}
-      </p>
-      <Button asChild variant="secondary" icon={IconArrowInbox}>
-        <a href={evidence.file.downloadUrl} target="_blank" rel="noreferrer">
-          {__("Download File")}
-        </a>
-      </Button>
+    <div className="space-y-4">
+      {preview}
+      {evidence.description && (
+        <p className="text-txt-secondary text-sm">{evidence.description}</p>
+      )}
     </div>
   );
 }

apps/console/src/pages/organizations/measures/tabs/MeasureEvidencesTab.tsx

@@ -1,4 +1,4 @@
-import { fileSize, fileType, formatDate, sprintf } from "@probo/helpers";
+import { fileSize, formatDate, sprintf } from "@probo/helpers";
 import { usePageTitle } from "@probo/hooks";
 import { useTranslate } from "@probo/i18n";
 import {
@@ -79,7 +79,7 @@ export const evidenceFragment = graphql`
       mimeType
       size
     }
-    type
+    description
     createdAt
     canDelete: permission(action: "core:evidence:delete")
   }
@@ -123,8 +123,8 @@ export default function MeasureEvidencesTab() {
       <SortableTable {...pagination}>
         <Thead>
           <Tr>
-            <Th>{__("Evidence name")}</Th>
-            <Th>{__("Type")}</Th>
+            <Th>{__("Description")}</Th>
+            <Th>{__("File type")}</Th>
             <Th>{__("File size")}</Th>
             <Th>{__("Created at")}</Th>
             <Th width={50}></Th>
@@ -248,13 +248,12 @@ function EvidenceRow(props: {
         />
       )}
       <Tr to={evidenceUrl}>
-        <Td>{evidence.file?.fileName}</Td>
         <Td>
-          {fileType(__, {
-            type: evidence.type,
-            mimeType: evidence.file?.mimeType || "",
-          })}
+          <span className="text-txt-secondary text-sm line-clamp-2">
+            {evidence.description || "—"}
+          </span>
         </Td>
+        <Td>{evidence.file?.mimeType || "—"}</Td>
         <Td>{fileSize(__, evidence.file?.size || 0)}</Td>
         <Td>{formatDate(evidence.createdAt)}</Td>
         <Td noLink>