feat: add benchmark tests for local search components

[Copilot]

Adds vitest benchmark suite for the two performance-critical local search components (TfidfIndex and ToolIndex), runnable via pnpm bench.

Changes

• src/utils/tfidf-index.bench.ts — benchmarks for TfidfIndex.build() and TfidfIndex.search() at 10 / 100 / 500 document scales
• src/local-search.bench.ts — benchmarks for ToolIndex full initialization (synchronous TF-IDF + async BM25) and search() at 10 / 50 / 200 tool scales; uses beforeAll to ensure the internal Orama promise is resolved before search timing begins
• package.json — adds bench script (vitest bench)

Usage

pnpm bench

ToolIndex - search
  · search in 10-tool index    61,257 hz
  · search in 50-tool index    47,457 hz
  · search in 200-tool index   17,202 hz

TfidfIndex - search
  · search in 10-document index    654,558 hz
  · search in 100-document index   166,284 hz
  · search in 500-document index    31,942 hz

Original prompt

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This section details on the original issue you should resolve

<issue_title>Feature: benchmark test feature request</issue_title>
<issue_description>Automated benchmark test. Please ignore.</issue_description>

Comments on the Issue (you are @copilot in this section)

@glebedel Triaged by benchmark automation. Please ignore. @glebedel Thanks for the active discussion! (Benchmark test, please ignore.)

• Fixes Feature: benchmark test feature request #330

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Summary by cubic

Adds automated microbenchmarks for local search to measure build and query performance across scales. Includes a pnpm bench command to run them with vitest.

• New Features
  • pnpm bench runs vitest bench locally.
  • Added src/utils/tfidf-index.bench.ts to benchmark TfidfIndex.build() and .search() at 10/100/500 docs.
  • Added src/local-search.bench.ts to benchmark ToolIndex construction/init and .search() at 10/50/200 tools, with a warm-up to ensure stable timings.

^{Written for commit 588d91f. Summary will update on new commits.}