Align tool schema docs with supported item_get and note_create behavior

[Copilot]

This tightens the new tool documentation surfaced through MCP so it matches the behavior introduced in the PR. It corrects the secret reference format documented by item_get and clarifies the custom field wording in note_create.

• Schema/docs alignment

  • Update item_get tool description to document secret references as op://vault/item/field
  • Update item_get.secretReference parameter docs to the same op://vault/item/field format
  • Clarify note_create.fields[].idOrTitle as a single identifier: id or title

• Regression coverage

  • Add focused tool-schema tests to assert the exposed descriptions for:
    • item_get secret reference format
    • note_create custom field wording

server.tool(
  "item_get",
  "... Accepts a secret reference (op://vault/item/field) or vault ID + item ID.",
  {
    secretReference: z
      .string()
      .optional()
      .describe("Secret reference in op://vault/item/field format."),
  },
);