fix(usage): correct cache cost semantics and silence pricing warn storm

- Split CostCalculator into per-app cache semantics: Anthropic's
  input_tokens is already fresh input, while Codex/Gemini include
  cached tokens in their prompt count. The old shared formula
  double-subtracted cache_read for Claude, under-billing input cost.
- Backfill now reads cost_multiplier from the per-log snapshot column
  instead of re-querying providers.meta, so historical rows are no
  longer rewritten with the current multiplier.
- Move the "pricing not found" warn out of find_model_pricing_row;
  emit it only when a brand new log is written, and skip placeholder
  models (unknown / empty / null / none) entirely.
- Broaden model id normalization: strip namespace prefixes
  (anthropic./openai./global./bedrock.), bedrock-style -vN suffixes,
  reasoning effort suffixes (-low/-medium/-high/-xhigh/-minimal),
  Claude Desktop's claude-<non-anthropic> wrapper, dot-to-dash for
  Claude, and try a LIKE prefix match for Claude short route ids
  (e.g. claude-haiku-4-5 -> claude-haiku-4-5-20251001).
- Fall back to request_model when the stored model is missing, so
  early Codex session rows with model=unknown can still be priced.

src-tauri/src/proxy/usage/logger.rs

@@ -4,7 +4,7 @@ use super::calculator::{CostBreakdown, CostCalculator, ModelPricing};
 use super::parser::TokenUsage;
 use crate::database::Database;
 use crate::error::AppError;
-use crate::services::usage_stats::find_model_pricing_row;
+use crate::services::usage_stats::{find_model_pricing_row, is_placeholder_pricing_model};
 use rust_decimal::Decimal;
 use std::{str::FromStr, time::SystemTime};
 
@@ -303,11 +303,21 @@ impl<'a> UsageLogger<'a> {
     ) -> Result<(), AppError> {
         let pricing = self.get_model_pricing(&pricing_model)?;
 
-        if pricing.is_none() {
+        let has_usage = usage.input_tokens > 0
+            || usage.output_tokens > 0
+            || usage.cache_read_tokens > 0
+            || usage.cache_creation_tokens > 0;
+
+        if pricing.is_none() && has_usage && !is_placeholder_pricing_model(&pricing_model) {
             log::warn!("[USG-002] 模型定价未找到，成本将记录为 0: {pricing_model}");
         }
 
-        let cost = CostCalculator::try_calculate(&usage, pricing.as_ref(), cost_multiplier);
+        let cost = CostCalculator::try_calculate_for_app(
+            &app_type,
+            &usage,
+            pricing.as_ref(),
+            cost_multiplier,
+        );
 
         let log = RequestLog {
             request_id,