feat: improve request pricing, model diagnostics, and client discovery

- Align response model handling with CPA-Manager-Plus and flag routing mismatches
- Add per-request costs and CSV export; fix mixed-context cost aggregation
- Display API-reported access types and move providers next to timestamps
- Use white table backgrounds and simplify cost and status displays
- Expand client discovery paths, validate executables, and prioritize installed clients
- Add model, pricing, client discovery, and UI regression tests

tests/usageModel.test.ts

@@ -0,0 +1,14 @@
+import { expect, test } from 'bun:test';
+import { usageModelDetails } from '../src/services/usageModel';
+
+test('compares reported response with routed model, not the requested alias', () => {
+  expect(usageModelDetails('gpt-routed', 'my-alias', 'gpt-routed')).toMatchObject({ showResolved: true, mismatch: false, showResponseInTooltip: false });
+  expect(usageModelDetails('gpt-routed', 'my-alias', 'my-alias')).toMatchObject({ mismatch: true });
+  expect(usageModelDetails('gpt-routed', '', 'different')).toMatchObject({ showResolved: false, mismatch: true });
+});
+
+test('missing response and route degrade without inventing model names', () => {
+  expect(usageModelDetails('gpt-routed', '', '  ')).toMatchObject({ requested: 'gpt-routed', mismatch: false });
+  expect(usageModelDetails('', 'alias', 'reported')).toMatchObject({ mismatch: false, showResponseInTooltip: true });
+  expect(usageModelDetails(' gpt-routed ', ' gpt-routed ', ' gpt-routed ')).toMatchObject({ showResolved: false, mismatch: false });
+});