feat: add session log usage tracking without proxy

Parse Claude Code JSONL session files (~/.claude/projects/) and Codex
SQLite database (~/.codex/state_5.sqlite) to track API usage without
requiring proxy interception. This enables usage statistics for users
who don't use the proxy feature.

Key changes:
- Add session_usage.rs: incremental JSONL parser with message.id dedup
- Add session_usage_codex.rs: import thread-level token data from Codex
- Add data_source column to proxy_request_logs (proxy/session_log/codex_db)
- Add session_log_sync table for tracking parse offsets
- Background sync every 60s + manual sync via DataSourceBar UI
- Schema migration v7→v8
- i18n support for zh/en/ja

src-tauri/src/services/usage_stats.rs

@@ -113,6 +113,8 @@ pub struct RequestLogDetail {
     pub status_code: u16,
     pub error_message: Option<String>,
     pub created_at: i64,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub data_source: Option<String>,
 }
 
 impl Database {
@@ -588,7 +590,7 @@ impl Database {
                     l.input_tokens, l.output_tokens, l.cache_read_tokens, l.cache_creation_tokens,
                     l.input_cost_usd, l.output_cost_usd, l.cache_read_cost_usd, l.cache_creation_cost_usd, l.total_cost_usd,
                     l.is_streaming, l.latency_ms, l.first_token_ms, l.duration_ms,
-                    l.status_code, l.error_message, l.created_at
+                    l.status_code, l.error_message, l.created_at, l.data_source
              FROM proxy_request_logs l
              LEFT JOIN providers p ON l.provider_id = p.id AND l.app_type = p.app_type
              {where_clause}
@@ -625,6 +627,7 @@ impl Database {
                 status_code: row.get::<_, i64>(20)? as u16,
                 error_message: row.get(21)?,
                 created_at: row.get(22)?,
+                data_source: row.get(23)?,
             })
         })?;
 
@@ -664,7 +667,7 @@ impl Database {
                     input_tokens, output_tokens, cache_read_tokens, cache_creation_tokens,
                     input_cost_usd, output_cost_usd, cache_read_cost_usd, cache_creation_cost_usd, total_cost_usd,
                     is_streaming, latency_ms, first_token_ms, duration_ms,
-                    status_code, error_message, created_at
+                    status_code, error_message, created_at, l.data_source
              FROM proxy_request_logs l
              LEFT JOIN providers p ON l.provider_id = p.id AND l.app_type = p.app_type
              WHERE l.request_id = ?",
@@ -694,6 +697,7 @@ impl Database {
                     status_code: row.get::<_, i64>(20)? as u16,
                     error_message: row.get(21)?,
                     created_at: row.get(22)?,
+                    data_source: row.get(23)?,
                 })
             },
         );