Please address the comments from this code review:

## Overall Comments
- In `EssenceFilterInitAction.Run`, `EssenceMode` defaults to `EssenceModePureOnly` when neither `FlawlessEssence` nor `PureEssence` is set; consider deriving `EssenceMode` from `EssenceTypes` or falling back to `EssenceModeBoth` to avoid surprising behavior when both options are false or omitted.
- In `EssenceFilterAfterBattleTierGateAction.Run`, JSON unmarshalling and unexpected `tier` values are effectively ignored; consider validating `params.Tier` and logging or short-circuiting on malformed input to make misconfigurations easier to detect.

## Individual Comments

### Comment 1
<location path="agent/go-service/essencefilter/state.go" line_range="52-54" />
<code_context>

 	// Essence types selected for this run (e.g. Flawless, Pure)
 	EssenceTypes []EssenceMeta
+	// EssenceMode derived from selection: flawless_only / pure_only / both
+	EssenceMode EssenceMode
+	// EncounteredTierBoundary is set when flawless-only mode encounters pure (inventory scan should stop)
+	EncounteredTierBoundary bool

</code_context>
<issue_to_address>
**suggestion (bug_risk):** EssenceMode is not reset in Reset, which can cause stale mode if Reset is reused outside Init

If `RunState.Reset()` is called on a reused state outside `EssenceFilterInit`, the previous run’s `EssenceMode` will be reused. To make `RunState` safer to use, `Reset` should initialize `EssenceMode` to a known default (e.g., `EssenceModeBoth`), with `Init` always overriding it as needed.

Suggested implementation:

```golang
	s.EssenceMode = EssenceModeBoth
	s.PhysicalItemCount = 0

```

This assumes:

1. `EssenceModeBoth` is the neutral/default mode constant already defined for `EssenceMode`.
2. The snippet shown (`s.PhysicalItemCount = 0`) is inside `func (s *RunState) Reset()`.

If `EssenceModeBoth` does not exist yet, you should define it in the `EssenceMode` enum/type definition (e.g., `const EssenceModeBoth EssenceMode = iota`) and ensure `EssenceFilterInit` keeps explicitly setting `EssenceMode` as appropriate for the run.
</issue_to_address>