Enable contracted funnel events in Kingston site.json

[truegoodcraft]

What

Enables the three contracted funnel signals for Kingston, per Jay's explicit go-ahead (2026-10-08). Two files changed:

• deployments/kingston/site.json — adds three event_payloads entries and one disclosure sentence:

  "resource_open":         { "event_name": "resource_open" },
  "install_prompt_show":   { "event_name": "install_prompt", "event_value": "show" },
  "install_prompt_dismiss": { "event_name": "install_prompt", "event_value": "dismiss" }

  Disclosure gains: "It also counts listing detail openings and install prompt shows and dismissals as broad totals only."
• tests/unit/kingston-analytics.test.ts — the Kingston contract test now pins the nine-event wire format (was six), asserting exact payloads, keys, and that the three new signals carry no attribution labels.

Contract alignment

• Matches the Lighthouse 1.35.0 accept contract exactly: resource_open and install_prompt show/dismiss as plain daily totals — no labels, no visit token, no listing identity.
• The new signals are deliberately not added to attribution.events; they stay unattributed per the contract.
• No visit_linkage (flag no longer exists), no schema changes, no other deployments touched.

Verification

• assertSite validation passes on the edited config.
• Kingston community check suite: 66 passed / 6 skipped.
• Targeted analytics unit tests: 15/15 pass.

Deployment note

Merging does not deploy by itself. Kingston goes live with these events only when release/kingston is advanced to the merge commit (npm run release -- --site deployments/kingston --ref <merge-sha> --publish) — Jay's call after review.