v0.11.0: pin/unpin node data tools

Edit-mode tools for managing pinned node data during workflow development. Pairs with n8n_scaffold_browser_bridge_node — scaffold a call, run it once, pin the output, iterate downstream nodes without re-spawning the browser.

Added

• n8n_pin_node_data — pin sample data on a single node so downstream nodes use it during development/testing without re-running the upstream node. Inputs: id, nodeName (validated to exist in the workflow), data (1-50 items; raw objects auto-wrap into {json: <object>}, fully-shaped {json, binary?} items pass through), optional merge: true to append (combined still ≤50), confirm: true. PUT body includes nodes/connections/settings/staticData from current state so those fields are not blanked. Response includes unpinHint since pinned data is easy to forget about.
• n8n_unpin_node_data — clear pinned data on one node (nodeName supplied) or the whole workflow (nodeName omitted). Idempotent: clearing a node that wasn't pinned returns ok: true, noop: true and never touches the API. Confirm-gated.

Notes

• Both go through PUT /workflows/:id (n8n's Public API doesn't have a dedicated pinData endpoint). They use client.saveWorkflow but bypass the snapshot+validation of n8n_save_workflow since pin/unpin only mutate pinData and the change is reversible via the sibling tool.
• 16 new tests; full suite 161/161 green.