docs(typescript-dev): fix README drift — dead local-mounts, false Copilot/Biome claims

[baxyz]

Summary

Found while investigating the "meta-feature" board card — this README had drifted from the manifest in four ways:

• local-mounts (superseded by dotfiles-sync since that feature's v1.0.0) was still listed as the recommended companion in four places (two JSON examples, "Complementary Features", "Perfect With").
• Copilot was claimed as bundled via essential-dev (intro, Features list, "Basic Setup" note, "General Tools" list) — stopped being true once Copilot moved to copilot-dev/github-dev.
• A "Biome - Dedicated feature available" line named a feature that doesn't exist anywhere in this repo.
• The listed TypeScript extension ID (ms-vscode.vscode-typescript-next) no longer matched the manifest's actual TypeScriptTeam.native-preview.

The manifest's own description field already said the right thing about Copilot — only the README had gone stale. Added a Version History section (previously missing) documenting this.

Test plan

• JSON validated
• Cross-checked every extension ID and dependency claim against the actual devcontainer-feature.json
• CI

🤖 Generated with Claude Code

[github-actions]

✅ PR Validation Passed

All checks passed!

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📋 Pipeline Status

	Job	Status
✅	🧾 Conventional Commits	passing
✅	🔖 Version Bump	passing
✅	🧪 Feature Tests	passing
✅	🐚 ShellCheck	passing

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_{🤖 Generated by @helpers4 CI • 2026-09-08}