fix(devshard): let a node replay its own pre-floor diffs on startup

[qdanik]

Problem

enforce inference tokens floor (#1391) added a MinTokensFloor check to applyStartInference. That check also runs on replay, so a node that served inferences before the floor landed cannot restart — it re-runs a rule written after its own diffs were made:

replay nonce 12: max_tokens below min_tokens floor: max_tokens 1, floor 64

Refusing the diff undoes nothing. It is already part of a recorded state root; the refusal only keeps the node down.

Fix

Separate authoring new work from replaying work already accepted.

• state.ApplyPersisted sets replayingPersisted under the same mutex as the apply and clears it via defer
• the floor check is skipped only on that path
• both replay call sites switch to it: user/recover.go (gateway) and cmd/devshardd/session/manager.go (host daemon)

Exactly one check is relaxed, and only the one guarding creation of new work. Live traffic still has to meet the floor.

Tests

Test	Package	Covers
TestApplyPersisted_ReplaysAStartWrittenBeforeTheFloor	state	the policy split, and that the relaxation does not outlive the call
TestRecoverSession_ReplaysADiffWrittenBeforeTheMaxTokensFloor	user	the gateway's recovery path, from a seeded sub-floor diff
TestRecoverSessions_ReplaysADiffWrittenBeforeTheMaxTokensFloor	cmd/devshardd/session	the host daemon's recovery path

Each fixture asserts ApplyLocal still rejects the diff before seeding it, so the test cannot silently stop reproducing the failure.

Mutation-tested — 4/4 killed, each verified to compile first: floor ignores the replay flag; flag never cleared; each replay site reverted to ApplyLocal.

state, user and cmd/devshardd/session pass in full.

[a-kuprin]

I would better name it ApplyLocalPersisted to keep some mental link with ApplyLocal

and keep the comment from ApplyLocal:

// ApplyLocal applies txs without signature verification. Used by the user
// to compute the post_state_root before signing the diff.