docs: clarify interoperability and compliance wording

Add docs/INTEROPERABILITY.md, an English scope document that describes
the project's interoperability and responsible-use practices: what it
distributes, how it handles local platform metadata and the MAC/AMFI
probe, how it keeps copyright and licence notices, how it avoids
access/authentication/integrity shortcuts, how it presents trademarks
and handles notices, and the user's responsibility for Riot's terms.

Update README, NOTICE, COMPLIANCE and PLATFORM_IDENTITY to link the
document and to state the opt-in window-helper and synthetic-identity
behaviour accurately. Add CONTRIBUTING with DCO sign-off and a scope
checklist.

Documentation-only change: no launcher, patch, build or test behaviour
changes.

Signed-off-by: 3AvisD <[email protected]>

docs/PLATFORM_IDENTITY.md

@@ -9,6 +9,12 @@ does not issue authentic Apple identities or change CPU, GPU, or security
 metadata. The overrides are for application compatibility; they are not intended
 to bypass anti-cheat, telemetry, licensing, or platform security controls.
 
+> **Synthetic, local metadata.** These values are not Apple-issued identifiers,
+> credentials or authentication tokens. Do not use them with Apple services or
+> to impersonate real hardware. They are not sent to Riot as authentication; the
+> official client authenticates through Riot's own flow. See the
+> [interoperability and compliance scope](INTEROPERABILITY.md).
+
 Preview an OpenCore `config.plist`, a flat GenSMBIOS JSON file, or an existing
 `darling-smbios.conf` without changing the selected prefix: