feat(snippets): add sdk-docs install canonicals for 9 SDKs

[kinyoklion]

Summary

Stacked on #428, which lands the shell-install validator infrastructure (with gem support and the multi-line last_pkg extractor). Adds 12 canonical .snippet.md files for the install / manifest <CodeBlock> regions in ld-docs's top-level reference pages that the original auto-port (#414) skipped per SDK-2300. All 12 get end-to-end shell-install validation against the real package registry.

Unblocks the corresponding marker insertions on ld-docs-private #7592.

Per-SDK file list + validation status

SDK	New snippet IDs	Validation
node-server-sdk	install-the-sdk-shell	✅ shell-install (npm)
node-client-sdk	install-the-sdk-installing-with-npm, …with-yarn	✅ shell-install (npm + yarn)
react-native-client-sdk	install-the-sdk-installing-react-native-sdk-v10, …adding-the-async-storage-dependency	✅ shell-install (yarn × 2)
ruby-server-sdk	install-the-sdk-shell	✅ shell-install (gem)
vue-client-sdk	install-the-sdk-installing-with-npm, …with-yarn	✅ shell-install (npm + yarn)
dotnet-server-sdk	install-the-sdk-shell	✅ shell-install (dotnet CLI; Install-Package legacy line stripped)
java-server-sdk	install-the-sdk-gradle	✅ shell-install (gradle DSL fragment in synthesized build.gradle)
php-server-sdk	install-the-sdk-shell	✅ shell-install (composer)
rust-server-sdk	install-the-sdk-shell	✅ shell-install (cargo)

go-server-sdk is intentionally not included — the "Shell install" mention in PR #7592's per-SDK table refers to a prose backtick quote of go get …, not an MDX CodeBlock.

Validator extensions (Dockerfile + harness)

The shell-install image grew from a node + python + go + ruby base to also include rust toolchain, php + composer, .NET SDK 8, and OpenJDK 17 + Gradle 8.10. Image is now ~2 GB — a CI-only artifact, cached per matrix cell, so the size pays for itself after the first build.

New harness LEAD cases:

• cargo — cargo init in a clean dir, run body, grep Cargo.toml for the package name.
• php — symlinks /opt/composer.phar into the working dir so the body's literal php composer.phar require … resolves; composer init; run body; check vendor/<pkg>/.
• dotnet — dotnet new console -n InstallSanity, cd in, run body, grep <PackageReference Include="…"> from the generated csproj.
• Install-Package strip — multi-line bodies that show the legacy NuGet PowerShell Install-Package form alongside the modern dotnet add package CLI form (for backward-compat documentation) get the legacy line stripped before LEAD detection. The dotnet CLI line is then validated via the case above.
• implementation (Gradle DSL fragment) — synthesizes a minimal build.gradle (plugins { id 'java' }, mavenCentral(), the body inserted in dependencies { … }); runs gradle dependencies; greps the dependency-tree output for the artifact name extracted from the body's name: '…' field.

Bug found + fixed inline

shell-install's last_pkg extractor was picking up trailing inline # comment text as a package name. Multi-line bodies like vue's npm install --save launchdarkly-vue-client-sdk\nnpm install @launchdarkly/observability # optional observability plugin\nnpm install @launchdarkly/session-replay # optional session replay plugin extracted plugin as the last package and then failed assert_node_modules looking for node_modules/plugin/. Fixed by stripping inline shell comments before field-splitting in awk. Benefits any sdk-info or observability install body with comments too.

Body fidelity

Each .snippet.md body is a byte-verbatim copy of what's in ld-docs today. Verified by running snippets render --target=ld-docs after a synthetic marker insertion and confirming the diff is exactly the marker comment — zero body bytes change.

Test plan

• go test ./... (from snippets/) passes.
• All 12 bindable snippets validate green locally against real package registries (npm × 4, yarn × 3, gem × 1, cargo × 1, composer × 1, dotnet CLI × 1, gradle × 1).
• Existing pre-feat(snippets): add sdk-docs install canonicals for 9 SDKs #439 shell-install bindings (sdk-info installs, observability installs from feat: Validation for ai-configs and observability slices #428) still pass — the comment-strip fix in last_pkg is a strict improvement.

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Note

Medium Risk
Moderate risk because it expands the shell-install validator’s Docker image/toolchain and adds new command-parsing/execution paths (cargo/composer/dotnet/gradle), which could impact CI reliability and install-snippet validation behavior.

Overview
Adds canonical sdk-docs “Install the SDK” snippet files for 9 SDKs (Node server/client, React Native, Vue, Ruby, Rust, PHP, .NET, Java) and binds them to the shell-install validator.

Expands the shell-install validator image and harness to validate additional install styles: installs Rust/cargo, PHP+Composer, .NET SDK, and JDK+Gradle; adds harness strategies for cargo add, php composer.phar require, dotnet add package, and Gradle implementation ... fragments; strips legacy NuGet Install-Package lines; and fixes package-name extraction to ignore inline # comments in multi-line bodies.

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