refactor: Move memory_usage into IngressHistoryStats

[alin-at-dfinity]

IngressHistoryState::memory_usage and IngressHistoryState::state_counts are always updated and validated in tandem. Move memory_usage into IngressHistoryStats and rename state_counts to stats, now that it's more generic than just counts by state.

[zeropath-ai]

✅ No security or compliance issues detected. Reviewed everything up to 4eb5854.

Security Overview

• 🔎 Scanned files: 5 changed file(s)
• 🔗 Scan Link: https://zeropath.com/app/repositories/f5e9d2bb-29a4-4b64-902a-391d65fd8b2d?scanId=ce4850f7-e5ce-4aea-8f12-70a51e278f05&codeScanTypes=PrScan&tab=issues

Detected Code Changes

Change Type	Relevant files
Refactor	► rs/replicated_state/src/lib.rs IngressHistoryState exports updated to match new fields ► rs/replicated_state/src/metadata_state.rs Replace memory_usage and state_counts with stats field; rename and restructure related methods and debug assertions ► rs/replicated_state/src/metadata_state/proto.rs Update From/TryFrom implementations to use stats instead of memory_usage/state_counts
Enhancement	► rs/replicated_state/src/metrics.rs Iterate over state.metadata.ingress_history.state_counts() directly (type adjustments)
Bug Fix	► rs/replicated_state/src/metadata_state.rs Align debug_asserts and computations to use compute_stats and new stats field instead of old memory_usage/state_counts ► rs/replicated_state/src/metadata_state/tests.rs Update test to reference ingress_history.stats.memory_usage instead of ingress_history.memory_usage

[Copilot]

Pull request overview

This PR refactors ingress history transient bookkeeping by consolidating memory usage tracking into IngressHistoryStats and renaming the internal “counts” concept into a more general stats aggregation, keeping related invariants updated together.

Changes:

• Move ingress history memory_usage tracking into IngressHistoryStats and store it under IngressHistoryState.stats.
• Refactor “counts-by-state” handling to flow through stats, including a single compute_stats() recomputation used in debug assertions and decoding.
• Update metrics emission and tests to use the refactored state_counts() iteration and new stats layout.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
rs/replicated_state/src/metrics.rs	Adjust metrics loop to iterate directly over ingress_history.state_counts() (now returns an iterator).
rs/replicated_state/src/metadata_state/tests.rs	Update tests to reference the refactored stats.memory_usage.
rs/replicated_state/src/metadata_state/proto.rs	Update debug validation and decoding to recompute/assign the unified stats.
rs/replicated_state/src/metadata_state.rs	Consolidate transient ingress history bookkeeping into stats, add compute_stats(), and update internal update paths.
rs/replicated_state/src/lib.rs	Stop re-exporting IngressHistoryStats after it becomes an internal implementation detail.

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