feat(analytics): add first-install lifecycle

[Rinat S (rsolmano)]

Problem

Additional analytics remains off until an explicit saved choice, while the finalized first-run experience primes sharing on when the dialog appears and treats ordinary dismissal as acceptance. Product analytics also lacks a durable first packaged-install event for acquisition denominators.

Approach

Separate startup prompting from runtime gating without changing the existing config fields: startup remains off/off, dialog mount persists the enabled preference, and confirmation only resolves the prompt. Add a server-only atomic installation marker and emit one property-minimal basic event before the first packaged app_started.

Changes

• Prime analyticsEnabled: true when the first-run dialog mounts; keep the dialog open until confirmation.
• Make Done/Close/Escape/backdrop confirm the current draft; explicit switch-off persists refusal immediately.
• Apply runtime analytics gating only for successful updates that explicitly touch analyticsEnabled.
• Keep concise startup copy and compact always-on/optional details in Settings → Privacy.
• Add app_installed once for binary/desktop, never source/CI/test, before app_started.
• Persist appInstalled: true through an atomic same-directory replacement while preserving the stable installation ID.
• Update unit, E2E, artifact-probe, and module specs for the exact lifecycle.

Screenshots

Not included — copy/control structure is unchanged; the behavioral state transition is covered by browser E2E.

Testing

• Focused server/store/artifact tests — 131 passed, 0 failed.
• Server, web, contracts, and artifact-tests typechecks — passed.
• e2e/analytics-consent.spec.ts + e2e/privacy.spec.ts — 16 passed.
• Binary build and smoke — passed.
• Biome and diff checks — passed with five pre-existing unrelated suppression warnings.
• Desktop build was unavailable locally because another Electrobun dev process holds the shared build lock; final stack CI/full E2E remains required.
• Independent reviewer verdict — Approve.

Checklist

• Fast gates pass: bun run lint, bun run typecheck, bun run test
• E2E suite passes for app-affecting changes (bun run e2e, or bun run e2e:full when touching agent behavior) — focused affected E2E passed; complete suite runs on the final combined stack
• Before/after screenshots are included for frontend changes, or marked not applicable
• Relevant SPEC.md / top-level specs updated to reflect any boundary, contract, or behavior change
• I have read the Contributing guide and agree to the Code of Conduct

[jetbrains-air]

Approved — ready to merge.