fix(mcp): add retry logic for Playwright MCP browser sidecar startup

[konard]

Summary

Fixes #123 — "Почему MCP сервер лежит с ошибкой?"

Root Cause

When Claude Code initializes MCP servers at startup, it runs the docker-git-playwright-mcp wrapper command. This wrapper connects to the browser sidecar container via CDP (Chrome DevTools Protocol) at http://dg-<repo>-browser:9223. If the browser container is not fully initialized yet, the curl command fails immediately (with set -euo pipefail), and the MCP server shows as "failed" in Claude Code's server management screen.

Solution

Add a configurable retry mechanism to the docker-git-playwright-mcp wrapper script:

• 10 retry attempts by default (configurable via MCP_PLAYWRIGHT_RETRY_ATTEMPTS)
• 2 second delay between attempts (configurable via MCP_PLAYWRIGHT_RETRY_DELAY)
• Progress logging to stderr for debugging (waiting for browser sidecar (attempt N/M)...)
• Clear error message if all retries are exhausted

This gives the browser sidecar up to ~20 seconds to become available, which should be sufficient for most startup scenarios.

Changes

• packages/lib/src/core/templates/dockerfile.ts: Add retry loop to docker-git-playwright-mcp wrapper
• packages/app/src/docker-git/cli/usage.ts: Document new environment variables
• packages/lib/tests/usecases/mcp-playwright.test.ts: Add test assertions for retry logic

Configuration

New environment variables (set via .orch/env/project.env or docker-compose environment):

Variable	Default	Description
MCP_PLAYWRIGHT_RETRY_ATTEMPTS	10	Number of retry attempts
MCP_PLAYWRIGHT_RETRY_DELAY	2	Delay in seconds between attempts

Test plan

• All existing tests pass (pnpm test)
• Type checking passes (pnpm run check)
• New test verifies retry logic is present in generated Dockerfile
• Manual test: Start docker-git project with --mcp-playwright and verify MCP server connects after browser sidecar startup

Mathematical guarantees

Invariant

• ∀t ∈ [1..max_attempts]: retry(t) → eventually(cdp_ready) ∨ timeout_error

Complexity

• Time: O(max_attempts × timeout_per_attempt) = O(10 × 12s) = O(120s) worst case
• Space: O(1) — no additional memory allocation in retry loop

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[konard]

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[konard]

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