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/i18n/locales/en.json

@@ -1121,8 +1121,7 @@
       "all": "All",
       "claude": "Claude Code",
       "codex": "Codex",
-      "gemini": "Gemini",
-      "hermes": "Hermes"
+      "gemini": "Gemini"
     },
     "dataSources": "Data Sources",
     "dataSource": {
@@ -1130,8 +1129,7 @@
       "session_log": "Session Log",
       "codex_db": "Codex DB",
       "codex_session": "Codex Session",
-      "gemini_session": "Gemini Session",
-      "hermes_session": "Hermes Session"
+      "gemini_session": "Gemini Session"
     },
     "sessionSync": {
       "trigger": "Sync session logs",

src/i18n/locales/ja.json

@@ -1121,8 +1121,7 @@
       "all": "すべて",
       "claude": "Claude Code",
       "codex": "Codex",
-      "gemini": "Gemini",
-      "hermes": "Hermes"
+      "gemini": "Gemini"
     },
     "dataSources": "データソース",
     "dataSource": {
@@ -1130,8 +1129,7 @@
       "session_log": "セッションログ",
       "codex_db": "Codex DB",
       "codex_session": "Codex セッション",
-      "gemini_session": "Gemini セッション",
-      "hermes_session": "Hermes セッション"
+      "gemini_session": "Gemini セッション"
     },
     "sessionSync": {
       "trigger": "セッションログを同期",

src/i18n/locales/zh.json

@@ -1121,8 +1121,7 @@
       "all": "全部",
       "claude": "Claude Code",
       "codex": "Codex",
-      "gemini": "Gemini",
-      "hermes": "Hermes"
+      "gemini": "Gemini"
     },
     "dataSources": "数据来源",
     "dataSource": {
@@ -1130,8 +1129,7 @@
       "session_log": "会话日志",
       "codex_db": "Codex 数据库",
       "codex_session": "Codex 会话日志",
-      "gemini_session": "Gemini 会话日志",
-      "hermes_session": "Hermes 会话日志"
+      "gemini_session": "Gemini 会话日志"
     },
     "sessionSync": {
       "trigger": "同步会话日志",