feat(lsp): add ESLint language server support

[amondnet]

Summary

• Add ESLint Language Server Protocol support to @pleaseai/code-lsp package
• Downloads and builds vscode-eslint from GitHub main branch
• Prerequisite check ensures eslint is installed in the project before starting
• Supports JS/TS files (.ts, .tsx, .js, .jsx, .mjs, .cjs, .mts, .cts) and Vue (.vue)

Changes

File	Description
packages/lsp/src/server.ts	Add EslintServer definition with download/build pattern
packages/lsp/src/index.ts	Export EslintServer
packages/lsp/CLAUDE.md	Update supported servers documentation
packages/lsp/test/unit/server.test.ts	Add unit tests for EslintServer

Test plan

• Typecheck passes
• Unit tests pass (74 tests, 0 failures)
• Code review completed
• Manual testing with project containing eslint

Closes #38

[codecov]

Codecov Report

❌ Patch coverage is 13.52941% with 147 lines in your changes missing coverage. Please review.
✅ Project coverage is 48.76%. Comparing base (74117d3) to head (15b9e6b).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/lsp/src/server.ts	13.01%	147 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #39      +/-   ##
==========================================
- Coverage   49.37%   48.76%   -0.62%     
==========================================
  Files          21       22       +1     
  Lines        4324     4561     +237     
==========================================
+ Hits         2135     2224      +89     
- Misses       2189     2337     +148     

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