feat: encrypted secrets vault across CLI, desktop, dashboard, and backend

Local vault (apps/cli): clean-room PRMVLT01 format — Argon2id →
XChaCha20-Poly1305, AEAD-bound header, atomic writes. vault:* / secrets:*
/ inject (primora:// refs) / agent credential broker (dummy tokens in the
child, real secret on the wire) / TTL sessions / stack:* operator group.

Project vault (backend): core.project_secrets, AES-256-GCM via the
platform encryptor. Metadata-only list, audit-logged reveal, and
secret://NAME refs resolved at job delivery — refs stored, values never.

Surfaces: dashboard Vault page (+ local-vault card under the Tauri
shell), desktop vault window via IPC to the primora binary,
secrets:* --remote CLI mode, metadata/write-only MCP tools so agents
consume secrets via secret:// refs without holding plaintext.

Authored By: TDvorak <[email protected]>

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/backend/internal/handlers/secrets.go

@@ -0,0 +1,87 @@
+package handlers
+
+import (
+	"errors"
+	"net/http"
+	"strings"
+
+	"github.com/gin-gonic/gin"
+	"github.com/jackc/pgx/v5"
+
+	"github.com/tdvorak/primora/apps/backend/internal/middleware"
+	apperrors "github.com/tdvorak/primora/apps/backend/internal/response"
+	"github.com/tdvorak/primora/apps/backend/internal/services"
+)
+
+func (h *HTTPHandler) secretError(c *gin.Context, err error) {
+	if errors.Is(err, pgx.ErrNoRows) {
+		apperrors.Abort(c, http.StatusNotFound, "not_found", "secret not found")
+		return
+	}
+	msg := err.Error()
+	if strings.Contains(msg, "invalid secret name") {
+		apperrors.Abort(c, http.StatusBadRequest, "bad_request", msg)
+		return
+	}
+	if strings.Contains(msg, "encryption is not configured") {
+		apperrors.Abort(c, http.StatusServiceUnavailable, "unavailable", msg)
+		return
+	}
+	h.handleError(c, err)
+}
+
+func (h *HTTPHandler) listProjectSecrets(c *gin.Context) {
+	actor, projectID, ok := h.actorAndProject(c)
+	if !ok {
+		return
+	}
+	result, err := h.Platform.ListProjectSecrets(c.Request.Context(), actor, projectID)
+	if err != nil {
+		h.secretError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"items": result})
+}
+
+func (h *HTTPHandler) setProjectSecret(c *gin.Context) {
+	actor, projectID, ok := h.actorAndProject(c)
+	if !ok {
+		return
+	}
+	var body services.SetProjectSecretInput
+	if !h.bindAndValidate(c, &body) {
+		return
+	}
+	body.Name = c.Param("name")
+	result, err := h.Platform.SetProjectSecret(c.Request.Context(), actor, projectID, body, middleware.RequestIDFromContext(c))
+	if err != nil {
+		h.secretError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, result)
+}
+
+func (h *HTTPHandler) deleteProjectSecret(c *gin.Context) {
+	actor, projectID, ok := h.actorAndProject(c)
+	if !ok {
+		return
+	}
+	if err := h.Platform.DeleteProjectSecret(c.Request.Context(), actor, projectID, c.Param("name"), middleware.RequestIDFromContext(c)); err != nil {
+		h.secretError(c, err)
+		return
+	}
+	c.Status(http.StatusNoContent)
+}
+
+func (h *HTTPHandler) revealProjectSecret(c *gin.Context) {
+	actor, projectID, ok := h.actorAndProject(c)
+	if !ok {
+		return
+	}
+	result, err := h.Platform.RevealProjectSecret(c.Request.Context(), actor, projectID, c.Param("name"), middleware.RequestIDFromContext(c))
+	if err != nil {
+		h.secretError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, result)
+}