fix(usage): pricing routing, SSE lifecycle, and validation hardening

* model pricing routing: extend prefix-match families (gpt-/o1-o5/
  gemini-/deepseek-/qwen-/glm-/kimi-/minimax-) with per-family dash
  thresholds so short base IDs like gpt-5 no longer mis-match
  gpt-5-mini; strip ISO and 8-digit date suffixes via UTF-8-safe
  byte matching so claude-haiku-4-5-20251001 falls back to
  claude-haiku-4-5 pricing
* SSE collector: SseUsageFinishGuard (RAII) guarantees finish() on
  early return or panic; AtomicBool fast path lets push() skip the
  Mutex once first-event time is recorded
* validation: shared validate_cost_multiplier / validate_pricing_source
  helpers across DAO and service layers; PRICING_SOURCE_RESPONSE /
  PRICING_SOURCE_REQUEST constants replace string literals; price
  fields in update_model_pricing now reject empty / non-decimal /
  negative input before INSERT
* backfill: add backfill_missing_usage_costs_for_model so a single
  price edit only scans matching rows instead of the full log table;
  startup backfill remains full-scan
* session_usage{,_codex,_gemini}: share find_model_pricing helper from
  usage_stats; metadata_modified_nanos centralizes mtime precision
* frontend: NON_NEGATIVE_DECIMAL_REGEX + isNonNegativeDecimalString
  replace three copies of the same multiplier regex; isUnpricedUsage
  surfaces zero-cost rows that have usage tokens (cached per row to
  avoid double evaluation); invalidate usageKeys.all on pricing mutate
  so backfilled rows refresh

src-tauri/src/services/session_usage_codex.rs

@@ -18,8 +18,10 @@ use crate::database::{lock_conn, Database};
 use crate::error::AppError;
 use crate::proxy::usage::calculator::{CostCalculator, ModelPricing};
 use crate::proxy::usage::parser::TokenUsage;
-use crate::services::session_usage::{get_sync_state, update_sync_state, SessionSyncResult};
-use crate::services::usage_stats::{should_skip_session_insert, DedupKey};
+use crate::services::session_usage::{
+    get_sync_state, metadata_modified_nanos, update_sync_state, SessionSyncResult,
+};
+use crate::services::usage_stats::{find_model_pricing, should_skip_session_insert, DedupKey};
 use rust_decimal::Decimal;
 use std::fs;
 use std::io::{BufRead, BufReader};
@@ -232,12 +234,7 @@ fn sync_single_codex_file(db: &Database, file_path: &Path) -> Result<(u32, u32),
     // 获取文件元数据
     let metadata = fs::metadata(file_path)
         .map_err(|e| AppError::Config(format!("无法读取文件元数据: {e}")))?;
-    let file_modified = metadata
-        .modified()
-        .ok()
-        .and_then(|t| t.duration_since(SystemTime::UNIX_EPOCH).ok())
-        .map(|d| d.as_secs() as i64)
-        .unwrap_or(0);
+    let file_modified = metadata_modified_nanos(&metadata);
 
     // 检查同步状态
     let (last_modified, last_offset) = get_sync_state(db, &file_path_str)?;
@@ -540,51 +537,7 @@ fn insert_codex_session_entry(
 
 /// 查找 Codex 模型定价（带归一化）
 fn find_codex_pricing(conn: &rusqlite::Connection, model_id: &str) -> Option<ModelPricing> {
-    let normalized = normalize_codex_model(model_id);
-
-    // 1. 精确匹配（归一化后的名称）
-    if let Some(pricing) = try_find_pricing(conn, &normalized) {
-        return Some(pricing);
-    }
-
-    // 2. LIKE 模糊匹配（兜底）
-    let pattern = format!("{normalized}%");
-    conn.query_row(
-        "SELECT input_cost_per_million, output_cost_per_million,
-                cache_read_cost_per_million, cache_creation_cost_per_million
-         FROM model_pricing WHERE model_id LIKE ?1 LIMIT 1",
-        rusqlite::params![pattern],
-        |row| {
-            Ok((
-                row.get::<_, String>(0)?,
-                row.get::<_, String>(1)?,
-                row.get::<_, String>(2)?,
-                row.get::<_, String>(3)?,
-            ))
-        },
-    )
-    .ok()
-    .and_then(|(i, o, cr, cc)| ModelPricing::from_strings(&i, &o, &cr, &cc).ok())
-}
-
-/// 精确匹配定价查询
-fn try_find_pricing(conn: &rusqlite::Connection, model_id: &str) -> Option<ModelPricing> {
-    conn.query_row(
-        "SELECT input_cost_per_million, output_cost_per_million,
-                cache_read_cost_per_million, cache_creation_cost_per_million
-         FROM model_pricing WHERE model_id = ?1",
-        rusqlite::params![model_id],
-        |row| {
-            Ok((
-                row.get::<_, String>(0)?,
-                row.get::<_, String>(1)?,
-                row.get::<_, String>(2)?,
-                row.get::<_, String>(3)?,
-            ))
-        },
-    )
-    .ok()
-    .and_then(|(i, o, cr, cc)| ModelPricing::from_strings(&i, &o, &cr, &cc).ok())
+    find_model_pricing(conn, &normalize_codex_model(model_id))
 }
 
 #[cfg(test)]