chore: add skills, subagent

[dkharms]

Description

Adds Claude Code tooling under .claude/ plus a contributor-facing CLAUDE.md.

• A several subagents where added -- code-reviewer, perf-analyzer, perf-architector;
• As well as several skills -- code-review, perf-analyze, perf-architect, code-navigation, and perf-loop (an autonomous optimization);

---

• I have read and followed all requirements in CONTRIBUTING.md;
• I used LLM/AI assistance to make this pull request;

If you have used LLM/AI assistance please provide model name and full prompt:

Model: Opus 5
Prompt: I was researching different repositories I like and how they approach the integration of AI in development. Ideas are mine, text was written by LLM. 

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 71.28%. Comparing base (38083e8) to head (90fac5e).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #521      +/-   ##
==========================================
- Coverage   71.30%   71.28%   -0.02%     
==========================================
  Files         250      250              
  Lines       21783    21783              
==========================================
- Hits        15532    15529       -3     
- Misses       5095     5099       +4     
+ Partials     1156     1155       -1     

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🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[forshev]

looks promising! let's support other agents, not only claude