fix(f02-mocks): apply complete f02 validation to write queue

[rvagg]

This is almost a reimplementation of the queue validation logic in f02, so any weight write operation should be validated as if it were hitting the real f02.

In here is:

fix(f02-mocks): give the weight ops one schedule-wide queue slot each 

SetWeightRecords and StepWeightRecords key their slot by op alone and hold
the whole batch as a single entry, so a second batch is rejected while one
is pending even when it names entirely different streams. The three
per-stream ops keep (id, op). A batch applies as one unit.

CancelPending addresses the weight slots with a null id, and rejects the
id/op shape mismatch in both directions.

and, taking it the whole-hog:

fix(f02-mocks): validate the projected queue 

A queued write walks the pending queue in effective-epoch order, applying each
entry to a candidate projection and validating from its own effective epoch.
Failing entries drop. The call is refused when the write does not survive its
position, or when the walk accepts fewer slots than it did without it.

Due writes are checked again at settle, since a cancellation can take away what
one depended on, and dropped if they no longer hold.

The weight sum is sampled at every breakpoint: clamped linears peak on a kink or
at the limit.

[Copilot]

Pull request overview

This PR updates the f02 Reward Actor mock to validate queued write operations using a projected-queue walk that mirrors f02 behavior, with special handling for schedule-wide weight-write slots so weight writes are admitted/settled according to full schedule validation.

Changes:

• Model SetWeightRecords / StepWeightRecords as schedule-wide, per-op queue slots (batch as a single pending entry) and adjust cancellation addressing (null-id shape).
• Add projected-schedule admission logic: walk pending writes in effective-epoch order, apply to a candidate projection, validate from each write’s effective epoch, and refuse writes that would strand previously-accepted entries.
• Re-check due writes at settle-time and drop (with an event) writes that no longer validate due to intervening cancellations.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
test/mocks/FVMRewardActor.sol	Implements schedule-wide weight batching and projected-queue validation, plus settle-time dropping of invalid due writes.
test/mocks/FVMRewardActor.t.sol	Adds/updates tests to cover schedule-wide weight slots, cancellation shape rules, and projected-schedule validation behaviors.

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