chore(usage): drop Hermes Agent tracking integration

Hermes aggregates all in-process API calls into a single sessions row
with the `model` field locked to the initial model, so the usage
dashboard cannot cleanly surface per-call billing context. Two rounds
of UI workarounds (raw mapping, then `<model> @ <host>` display) did
not resolve the user-facing confusion, so the whole tracking
integration is dropped for now.

Removes session_usage_hermes service (and its 17 tests), sync wiring
in commands/usage.rs and lib.rs, _hermes_session/hermes_session
entries in usage_stats SQL (provider_name_coalesce CASE and
effective_usage_log_filter IN clause), frontend Tab/banner/dropdown/
icon entries, and four i18n keys per locale.

Hermes app integration outside usage tracking (proxy routing,
session manager, config) is preserved. Pre-existing hermes rows in
proxy_request_logs are left as orphans — filtered out by the
updated SQL and never surfaced in the UI.

src/types/usage.ts

@@ -129,7 +129,7 @@ export interface UsageRangeSelection {
   customEndDate?: number;
 }
 
-export type AppTypeFilter = "all" | "claude" | "codex" | "gemini" | "hermes";
+export type AppTypeFilter = "all" | "claude" | "codex" | "gemini";
 
 export interface StatsFilters {
   timeRange: UsageRangePreset;