Replace private uses of DataStructures::List/Queue/OrderedList/Map/Hash with the standard library (std migration, stage 2) #60

Follow-up to #50 / #58, second of three stages. Depends on #59.

Scope

The general-purpose containers are used 768 times across the library; DataStructures::List alone accounts for 402. This stage converts every use that is not part of a public signature: member variables, locals and private helpers in the 36 Source/src/*.cpp files and in the private sections of headers. Public method and virtual signatures are left exactly as they are (that is stage 3).

Approach

• Mechanical but large; do it per subsystem (reliability layer, peer, each plugin) in separate commits so bisecting stays possible.
• Where a value crosses a public boundary (a private std::vector that must be handed out through a still-public DataStructures::List&), add a small conversion at the boundary rather than changing the signature; stage 3 removes those conversions.
• Watch for RemoveAtIndexFast (swap-remove, order not preserved) and ring-buffer Queue capacity assumptions; both change iteration order or memory behaviour when swapped for standard types.
• Allocations through these containers currently go via rakMalloc/OP_NEW with file-and-line tracking. Decide once whether the standard containers get a std::allocator shim onto rakMalloc or whether that tracking is dropped for them; apply uniformly.

Acceptance

• No DataStructures::List|Queue|OrderedList|Map|Hash use remains in Source/src/ or in private/protected sections of headers.
• Public declarations unchanged.
• Full suite green on Linux (Debug, Release), macOS, Windows; samples build.