feat(workspace): add repos JSONB field for GitHub repository URLs

Add a `repos` JSONB column to the workspace table for storing
associated repository URLs and descriptions. This enables the daemon
to clone repos and set up git worktrees for agent task execution.

Structure: [{"url": "https://github.com/org/repo", "description": "..."}]

- Migration 014: adds repos column with default '[]'
- UpdateWorkspace query: supports updating repos
- Workspace API: returns repos in GET, accepts in PUT

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/internal/handler/workspace.go

@@ -20,6 +20,7 @@ type WorkspaceResponse struct {
 	Description *string `json:"description"`
 	Context     *string `json:"context"`
 	Settings    any     `json:"settings"`
+	Repos       any     `json:"repos"`
 	CreatedAt   string  `json:"created_at"`
 	UpdatedAt   string  `json:"updated_at"`
 }
@@ -32,6 +33,13 @@ func workspaceToResponse(w db.Workspace) WorkspaceResponse {
 	if settings == nil {
 		settings = map[string]any{}
 	}
+	var repos any
+	if w.Repos != nil {
+		json.Unmarshal(w.Repos, &repos)
+	}
+	if repos == nil {
+		repos = []any{}
+	}
 	return WorkspaceResponse{
 		ID:          uuidToString(w.ID),
 		Name:        w.Name,
@@ -39,6 +47,7 @@ func workspaceToResponse(w db.Workspace) WorkspaceResponse {
 		Description: textToPtr(w.Description),
 		Context:     textToPtr(w.Context),
 		Settings:    settings,
+		Repos:       repos,
 		CreatedAt:   timestampToString(w.CreatedAt),
 		UpdatedAt:   timestampToString(w.UpdatedAt),
 	}
@@ -169,6 +178,7 @@ type UpdateWorkspaceRequest struct {
 	Description *string `json:"description"`
 	Context     *string `json:"context"`
 	Settings    any     `json:"settings"`
+	Repos       any     `json:"repos"`
 }
 
 func (h *Handler) UpdateWorkspace(w http.ResponseWriter, r *http.Request) {
@@ -204,6 +214,10 @@ func (h *Handler) UpdateWorkspace(w http.ResponseWriter, r *http.Request) {
 		s, _ := json.Marshal(req.Settings)
 		params.Settings = s
 	}
+	if req.Repos != nil {
+		r, _ := json.Marshal(req.Repos)
+		params.Repos = r
+	}
 
 	ws, err := h.Queries.UpdateWorkspace(r.Context(), params)
 	if err != nil {