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>

pkg/cmd/evidence/list/list.go

@@ -0,0 +1,199 @@
+// Copyright (c) 2025-2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package list
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/spf13/cobra"
+	"go.probo.inc/probo/pkg/cli/api"
+	"go.probo.inc/probo/pkg/cmd/cmdutil"
+)
+
+const listQuery = `
+query($id: ID!, $first: Int, $after: CursorKey, $orderBy: EvidenceOrder) {
+  node(id: $id) {
+    __typename
+    ... on Measure {
+      evidences(first: $first, after: $after, orderBy: $orderBy) {
+        totalCount
+        edges {
+          node {
+            id
+            state
+            type
+            url
+            description
+            createdAt
+          }
+        }
+        pageInfo {
+          hasNextPage
+          endCursor
+        }
+      }
+    }
+  }
+}
+`
+
+type evidence struct {
+	ID          string  `json:"id"`
+	State       string  `json:"state"`
+	Type        string  `json:"type"`
+	URL         string  `json:"url"`
+	Description *string `json:"description"`
+	CreatedAt   string  `json:"createdAt"`
+}
+
+func NewCmdList(f *cmdutil.Factory) *cobra.Command {
+	var (
+		flagMeasure  string
+		flagLimit    int
+		flagOrderBy  string
+		flagOrderDir string
+		flagOutput   *string
+	)
+
+	cmd := &cobra.Command{
+		Use:     "list",
+		Short:   "List evidences for a measure",
+		Aliases: []string{"ls"},
+		Example: `  # List evidences for a measure
+  prb evidence list --measure <measure-id>
+
+  # Output as JSON
+  prb evidence ls --measure <measure-id> --output json`,
+		Args: cobra.NoArgs,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			if err := cmdutil.ValidateOutputFlag(flagOutput); err != nil {
+				return err
+			}
+
+			cfg, err := f.Config()
+			if err != nil {
+				return err
+			}
+
+			host, hc, err := cfg.DefaultHost()
+			if err != nil {
+				return err
+			}
+
+			client := api.NewClient(
+				host,
+				hc.Token,
+				"/api/console/v1/graphql",
+				cfg.HTTPTimeoutDuration(),
+			)
+
+			variables := map[string]any{
+				"id": flagMeasure,
+			}
+
+			if flagOrderBy != "" {
+				if err := cmdutil.ValidateEnum("order-by", flagOrderBy, []string{"CREATED_AT"}); err != nil {
+					return err
+				}
+				variables["orderBy"] = map[string]any{
+					"field":     flagOrderBy,
+					"direction": flagOrderDir,
+				}
+			}
+
+			evidences, totalCount, err := api.Paginate(
+				client,
+				listQuery,
+				variables,
+				flagLimit,
+				func(data json.RawMessage) (*api.Connection[evidence], error) {
+					var resp struct {
+						Node *struct {
+							Typename  string                   `json:"__typename"`
+							Evidences api.Connection[evidence] `json:"evidences"`
+						} `json:"node"`
+					}
+					if err := json.Unmarshal(data, &resp); err != nil {
+						return nil, err
+					}
+					if resp.Node == nil {
+						return nil, fmt.Errorf("measure %s not found", flagMeasure)
+					}
+					if resp.Node.Typename != "Measure" {
+						return nil, fmt.Errorf("expected Measure node, got %s", resp.Node.Typename)
+					}
+					return &resp.Node.Evidences, nil
+				},
+			)
+			if err != nil {
+				return err
+			}
+
+			if *flagOutput == cmdutil.OutputJSON {
+				return cmdutil.PrintJSON(f.IOStreams.Out, evidences)
+			}
+
+			if len(evidences) == 0 {
+				_, _ = fmt.Fprintln(f.IOStreams.Out, "No evidences found.")
+				return nil
+			}
+
+			rows := make([][]string, 0, len(evidences))
+			for _, e := range evidences {
+				desc := "-"
+				if e.Description != nil && *e.Description != "" {
+					d := *e.Description
+					if len(d) > 60 {
+						d = d[:57] + "..."
+					}
+					desc = d
+				}
+				rows = append(rows, []string{
+					e.ID,
+					e.Type,
+					e.State,
+					desc,
+					cmdutil.FormatTime(e.CreatedAt),
+				})
+			}
+
+			t := cmdutil.NewTable("ID", "TYPE", "STATE", "DESCRIPTION", "CREATED").Rows(rows...)
+
+			_, _ = fmt.Fprintln(f.IOStreams.Out, t)
+
+			if totalCount > len(evidences) {
+				_, _ = fmt.Fprintf(
+					f.IOStreams.ErrOut,
+					"\nShowing %d of %d evidences\n",
+					len(evidences),
+					totalCount,
+				)
+			}
+
+			return nil
+		},
+	}
+
+	cmd.Flags().StringVar(&flagMeasure, "measure", "", "Measure ID (required)")
+	cmd.Flags().IntVarP(&flagLimit, "limit", "L", 30, "Maximum number of evidences to list")
+	cmd.Flags().StringVar(&flagOrderBy, "order-by", "", "Order by field (CREATED_AT)")
+	cmd.Flags().StringVar(&flagOrderDir, "order-direction", "DESC", "Sort direction (ASC, DESC)")
+	flagOutput = cmdutil.AddOutputFlag(cmd)
+
+	_ = cmd.MarkFlagRequired("measure")
+
+	return cmd
+}