feat: add note_create tool for Secure Note items

[Copilot]

Adds a note_create MCP tool that creates ItemCategory.SecureNote items in a 1Password vault, closing the gap left after password_create was introduced.

New tool: note_create

Inputs: vaultId, title, notes?, tags?, fields?

Custom fields follow the same shape used by item_edit:

fields: [
  { idOrTitle: "apiKey", type: "concealed", value: "abc123" },
  { idOrTitle: "env",    type: "text",      value: "prod", section: "s1" }
]

Changes

• src/tools/note-create.ts — new tool; maps type: 'text'|'concealed' to sdk.ItemFieldType, passes sectionId when provided; fully typed via sdk.ItemField[] with no any
• src/tools/index.ts — registers registerNoteCreate
• tests/tools.test.ts — bumps expected tool count 8→9; adds four note_create tests (happy path, tags+fields arg shape verification, SDK error, missing items.create)