fix: restore pnpm.onlyBuiltDependencies in plugin package.json for standalone install

[linliehanfeng]

Problem

When this plugin is installed via Claude Code's plugin marketplace (/plugin install understand-anything@understand-anything), only the understand-anything-plugin/ subdirectory is copied into ~/.claude/plugins/cache/. The monorepo root package.json is not part of the installed payload.

Since PR #142's review-feedback fix (commit 2083342) moved pnpm.onlyBuiltDependencies from understand-anything-plugin/package.json to the monorepo root, end-user installs no longer carry any allowlist for native build scripts. On pnpm v10 (which errors instead of warning on ignored builds), pnpm install inside the installed plugin directory fails:

ERR_PNPM_IGNORED_BUILDS Ignored build scripts: esbuild@0.25.12,
  tree-sitter-c-sharp@0.23.5, tree-sitter-c@0.23.6, tree-sitter-cpp@0.23.4,
  tree-sitter-go@0.25.0, tree-sitter-java@0.23.5, tree-sitter-javascript@0.23.1,
  tree-sitter-javascript@0.25.0, tree-sitter-php@0.23.12,
  tree-sitter-python@0.25.0, tree-sitter-ruby@0.23.1, tree-sitter-rust@0.24.0,
  tree-sitter-typescript@0.23.2

Run "pnpm approve-builds" to pick which dependencies should be allowed to run scripts.
ERROR Command failed with exit code 1: pnpm install

This blocks the /understand skill at Phase 0 step 1.5 ("Ensure the plugin is built") — packages/core/dist/index.js cannot be produced and the skill aborts with the standard "Install Node.js ≥ 22 and pnpm ≥ 10" hint.

Repro

1. Fresh machine with pnpm v10+ installed
2. In Claude Code:

   /plugin marketplace add https://github.com/Lum1104/Understand-Anything
   /plugin install understand-anything@understand-anything
   /understand
   

3. Phase 0.5 fails on pnpm install due to ignored build scripts.

Fix

Re-add pnpm.onlyBuiltDependencies to understand-anything-plugin/package.json, mirroring the list in the monorepo root (plus sharp, which is already in the root copy).

This is intentional duplication:

Consumer	Reads from
Contributor running pnpm install from monorepo root	root package.json
End-user installing via CC plugin marketplace (only the subdir is copied)	understand-anything-plugin/package.json

Without this, every fresh CC plugin install hits ERR_PNPM_IGNORED_BUILDS until the user manually edits the package.

Verified

After the change, on a clean pnpm cache:

pnpm install --no-frozen-lockfile
# … node-gyp-build ran for 12 tree-sitter parsers + esbuild postinstall …
# Done in 16.4s using pnpm v11.1.1
pnpm --filter @understand-anything/core build
ls packages/core/dist/index.js  # exists, 2.2KB

Then /understand proceeds through Phases 0–7 and writes a valid knowledge-graph.json.