Fix stale get_accessory reads end to end

[ankjaers]

Problem

PR #70 added a hard timeout around HomeKit characteristic reads, but the resulting success/failure value is discarded before get_accessory is serialized.

When HMCharacteristic.readValue times out or returns an error, HMCharacteristic.value can still contain its previous value. The socket then returns that last-known value inside success: true, and neither the CLI nor the stdio MCP server can tell whether it was observed by the current request.

Changes

• Capture a read attestation inside each HomeKit completion handler.
• Add an additive get_accessory wire contract:
  • top-level refreshed
  • read_attempted and read_succeeded counts
  • per-readable-characteristic read.succeeded
  • completion-bound read.observed_at for successful reads only
• Do not update the accessory cache from failed reads.
• Make default CLI get fail nonzero for failed, missing, malformed, or internally inconsistent freshness metadata.
• Apply the same fail-closed validation to the active stdio MCP get path.
• Preserve stale output only when callers explicitly request --no-refresh / no_refresh: true.
• Keep demo responses wire-compatible and add deterministic Swift and Node regression tests.
• Always rebuild the MCP bundle during an Xcode build when Node dependencies are available, so imported lib/* changes cannot be skipped by an incomplete mtime check.

Example successful metadata:

{
  "refreshed": true,
  "read_attempted": 1,
  "read_succeeded": 1,
  "services": [
    {
      "characteristics": [
        {
          "read": {
            "succeeded": true,
            "observed_at": "2026-09-10T14:00:00.125Z"
          }
        }
      ]
    }
  ]
}

A failed read emits succeeded: false without an observation timestamp and makes the request-level refreshed value false.

Scope

This PR attests the request-oriented get_accessory path. Bulk cache-warming policy is intentionally unchanged and can be hardened independently without coupling this wire fix to cache-generation semantics.

Verification

• swift test — 187 tests passed
• npm ci — 0 vulnerabilities
• npm run test:mcp — 3 tests passed
• npm run build:mcp — passed
• Unsigned Mac Catalyst HomeClaw build — passed with Xcode 26.6
• Committed MCP bundle syntax (node --check) — passed

The automated Catalyst build is intentionally unsigned, matching this repository's CI. The freshness behavior uses deterministic payload tests rather than timing-based sleeps.

[ankjaers]

👋
There is a real person behind this pr. Feedback and concerns is appreciated