[Review] feat: AI code completion & intellisense for python editor

[govambam]

Recreated from writer#1263 for Macroscope review.

Original PR: writer#1263 by @bybash
Status: open (open)

Recreated using direct PR head fetch - exact current state preserved.

Original PR: writer#1263

[macroscopeapp]

Add Python LSP-backed code completion and diagnostics to the Builder embedded editor in edit mode and expose /api/lsp-config and /api/code-completion (50KB max request) from the backend

Introduce a backend pylsp lifecycle via writer.LSPManager with WebSocket transport and new edit-mode endpoints, and wire a Monaco LSP client with completion, diagnostics filtering, and optional AI completion using monacopilot, including VSCode service overrides and build/runtime dependencies.

📍Where to Start

Start with the server lifecycle and endpoints in writer.serve.get_asgi_app and writer.serve.code_completion within serve.py, then review the LSP client bootstrap in lspClient.ts and its initialization in lspSetup.ts.

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Macroscope summarized 421e788.