feat: unflag Ruby gem support and add e2e bundler tests

Remove the `gem` feature flag so Ruby gem support is always compiled in,
matching npm and PyPI which are already default-on. This ensures gem
support ships in every release binary built with `cargo build --release`.

- Remove `gem = []` from both Cargo.toml feature sections
- Remove all `#[cfg(feature = "gem")]` gates from crawler module,
  Ecosystem enum, PURL functions, and ecosystem dispatch
- Rewrite e2e_gem.rs with full bundler lifecycle tests targeting
  activestorage@5.2.0 (CVE-2022-21831) with 3-file hash verification
- Add Ruby 3.2 setup step in CI for e2e_gem suite
- Update READMEs to reflect gem as default, not feature-flagged

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: mikolalysenko

.github/workflows/ci.yml

@@ -120,5 +120,12 @@ jobs:
         with:
           python-version: "3.12"
 
+      - name: Setup Ruby
+        if: matrix.suite == 'e2e_gem'
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: '3.2'
+          bundler-cache: false
+
       - name: Run e2e tests
         run: cargo test -p socket-patch-cli --all-features --test ${{ matrix.suite }} -- --ignored

Cargo.lock

@@ -66,7 +66,7 @@ cargo install socket-patch-cli
 By default this builds with npm and PyPI support. For additional ecosystems:
 
 ```bash
-cargo install socket-patch-cli --features cargo,golang,maven,gem,composer,nuget
+cargo install socket-patch-cli --features cargo,golang,maven,composer,nuget
 ```
 
 ## Quick Start

README.md

@@ -26,7 +26,6 @@ tempfile = { workspace = true }
 [features]
 default = []
 cargo = ["socket-patch-core/cargo"]
-gem = ["socket-patch-core/gem"]
 golang = ["socket-patch-core/golang"]
 maven = ["socket-patch-core/maven"]
 composer = ["socket-patch-core/composer"]

crates/socket-patch-cli/Cargo.toml

@@ -7,7 +7,6 @@ use std::path::PathBuf;
 
 #[cfg(feature = "cargo")]
 use socket_patch_core::crawlers::CargoCrawler;
-#[cfg(feature = "gem")]
 use socket_patch_core::crawlers::RubyCrawler;
 #[cfg(feature = "golang")]
 use socket_patch_core::crawlers::GoCrawler;
@@ -141,7 +140,6 @@ pub async fn find_packages_for_purls(
     }
 
     // gem
-    #[cfg(feature = "gem")]
     if let Some(gem_purls) = partitioned.get(&Ecosystem::Gem) {
         if !gem_purls.is_empty() {
             let ruby_crawler = RubyCrawler;
@@ -323,7 +321,6 @@ pub async fn crawl_all_ecosystems(
         all_packages.extend(cargo_packages);
     }
 
-    #[cfg(feature = "gem")]
     {
         let ruby_crawler = RubyCrawler;
         let gem_packages = ruby_crawler.crawl_all(options).await;
@@ -468,7 +465,6 @@ pub async fn find_packages_for_rollback(
     }
 
     // gem
-    #[cfg(feature = "gem")]
     if let Some(gem_purls) = partitioned.get(&Ecosystem::Gem) {
         if !gem_purls.is_empty() {
             let ruby_crawler = RubyCrawler;