…off*Ms

HttpTransportTests pinned the backoff schedule with literal millisecond
numbers (5_000 / 10_000 / 20_000 / 40_000 / 60_000). Constants.HttpBackoff*Ms
now own those values, but the tests still hardcoded the numbers, so a
change to the constants would have flipped production behaviour while
the tests kept passing against the old expectations.

Switch every BackoffMs / NextAttemptAt assertion to derive from
Constants.HttpBackoff{1st,2nd,3rd,4th,Cap}Ms.

Follow-up to SDK-272 (centralisation of duplicated literals).

ParseLowercaseString was added in the SDK-272 stack as the inverse of
ToLowercaseString and consumed by the sample app to map wire strings
back to the enum. It had no direct test, so a typo in any of the eight
case branches or in the Custom fallback would land silently.

Add three parametrised cases:
- Each known enum value maps from its lowercase wire form.
- Mixed-case ("Steam", "STEAM", "Passport") still resolves
  via ToLowerInvariant, matching the documented behaviour.
- null, empty, and unknown values fall back to Custom (the parser
  never throws so producer code always gets a usable enum).

Follow-up to SDK-272 (centralisation of duplicated literals).

…l platforms

Init's lowercase-normalisation tests covered "Steam" / "STEAM" / "steam"
but not the other four public DistributionPlatforms values (Epic, GOG,
Itch, Standalone). Adding a sixth platform would land without coverage.

Add a parametrised Init_LowercasesDistributionPlatform_AcrossAllPublicValues
test that takes each public DistributionPlatforms constant, uppercases
it, runs Init, and asserts the canonical lowercase form is restored.

Follow-up to SDK-272 (centralisation of duplicated literals).

…sages

The two centralised message catalogues had no direct unit tests.
Behavioural tests observed wording loosely via Does.Contain assertions,
which let typos and partial rewords through.

Add MessagesTests.cs with one fixture per catalogue. Each constant /
formatter has an exact-string assertion. A reword anywhere in the
catalogue now fails the build.

Follow-up to SDK-272 (centralisation of duplicated literals).

Per the user's "everything random goes in a constant" stance, this is
applied against the previous session's recommendation that scenario
descriptors read better inline. Recording the override on the user's
explicit request.

Follow-up to SDK-272 (centralisation of duplicated literals).

…leAppCustomEvents

The sample-app demo catalogue (sign_up, sign_in, email_acquired,
wishlist_add, wishlist_remove, game_page_viewed, link_clicked,
screen_viewed) had its event-name strings inline at every call site.
A rename touches the catalogue, the screen_viewed Track call, and
each Unity live-fire test that drives the catalogue UI.

Move the eight names into a new internal SampleAppCustomEvents class
under the sample-app Scripts assembly. Update AudienceSample.Events.cs,
AudienceSample.cs (screen_viewed Track), and SampleAppLiveFireTests.cs
(button and field lookups by event name) to reference the constants.

Per the user's "everything random goes in a constant" stance,
applied against the previous session's recommendation that the demo
content read better inline. Recording the override on the user's
explicit request.

Follow-up to SDK-272 (centralisation of duplicated literals).

…mpleAppCustomEventPropertyKeys

The sample-app demo catalogue, screen_viewed Track call, and the
typed-event live-fire tests had property keys (method, source,
gameId, platform, gameName, slug, url, label, path) inline at every
call site. Each key duplicates between the catalogue's EventField
definition and the live-fire test's UI lookup.

Add SampleAppCustomEventPropertyKeys alongside SampleAppCustomEvents
(mirrors the SDK's EventPropertyKeys naming) and reference the
constants from AudienceSample.Events.cs, AudienceSample.cs (the
screen_viewed props dictionary), and SampleAppLiveFireTests.cs (the
TypedEventField field-name lookups).

Includes gameName and slug beyond the user's listed seven keys: same
inline-property-key category, same migration treatment.

Per the user's "everything random goes in a constant" stance,
applied against the previous session's recommendation that the demo
content read better inline. Recording the override on the user's
explicit request.

Follow-up to SDK-272 (centralisation of duplicated literals).

…d lookups in live-fire tests

SampleAppLiveFireTests filled the Resource, Purchase, and
MilestoneReached typed-event forms by looking up TextFields with
inline property-name strings ("currency", "amount", "value", "name").
The SDK already centralises these as EventPropertyKeys.Currency /
.Amount / .Value / .Name, made visible to the sample-app tests
through the existing InternalsVisibleTo grant.

Reference EventPropertyKeys.X from the five lookup sites instead of
re-typing the wire-format strings.

Discovered during the sample-app demo property-key centralisation
pass; kept separate because these keys belong to the SDK's typed-event
surface, not the sample-app demo catalogue.

Per the user's "everything random goes in a constant" stance.

Follow-up to SDK-272 (centralisation of duplicated literals).