feat: entry update links existing secrets (link_secret_names)

- secrets-core: update flow validates and applies secret links
- secrets-mcp: MCP tool params and UI for managing links on edit
- Align errors and templates; minor crypto/.gitignore tweaks

Made-with: Cursor

Cargo.lock

@@ -1969,7 +1969,7 @@ dependencies = [
 
 [[package]]
 name = "secrets-mcp"
-version = "0.4.0"
+version = "0.5.0"
 dependencies = [
  "anyhow",
  "askama",