Wire PostHog into the cookie-banner React example

Add a deferred PostHog wiring under examples/cookie-banner-react that
boots posthog.init() inside the probo-ready handler and derives
cookieless_mode and opt_out_capturing_by_default from the consent
snapshot for the category flagged with posthog_consent.

Driving the init args off the snapshot rather than consent_mode plugs
two cases the simpler "consent_mode alone" rule got wrong:

  * OPT_OUT regulation, returning rejector: init would have booted in
    on_reject + capture-on, fired a $pageview synchronously, and only
    then called opt_out_capturing(). That single captured pageview
    (and the posthog cookie) leaked on every page load.
  * OPT_IN regulation, returning acceptor: init would have forced
    "always" + opt-out, costing the visitor cookies and a one-tick
    capture delay even though they had already consented.

The snapshot already encodes the regulation default
(buildDefaultConsentData on the cookie-banner client returns true for
non-necessary categories under OPT_OUT and false under OPT_IN) and any
persisted answer from a prior visit, so a single boolean drives both
init args.

Re-export the public domain types (BannerConfig, Category, Regulation,
ConsentAction, ConsentRecord, CookieItem, VisitorConsent) from
@probo/cookie-banner so the example can type the probo-ready event
detail without duck-typing it.

Adopt the PUBLIC_ env prefix in Vite so the example reads the same env
var names (PUBLIC_COOKIE_BANNER_ID, PUBLIC_COOKIE_BANNER_API_BASE_URL,
PUBLIC_POSTHOG_API_KEY) already used on getprobo.com, and add a
matching .env.example.

Ignore *.tsbuildinfo at the repo root; TypeScript's incremental cache
is machine-local and does not belong in the tree.

Signed-off-by: Émile Ré <emile@probo.com>

.gitignore

@@ -14,6 +14,7 @@ sbom-docker.json
 *.pem
 *.crt
 *.key
+*.tsbuildinfo
 compose/keycloak/probo-realm.json
 .sandbox.env