feat(install): route the perry install wrapper through Socket Firewall when available

changelog.d/6914-install-sfw-firewall.md

@@ -0,0 +1 @@
+**`perry install` rides Socket Firewall:** the secure install wrapper (#738) now runs the wrapped `bun`/`npm` install *through* an `sfw` binary when one is available, adding network-time malware scanning to the existing offline scan + lifecycle-script allowlist: wire → tree → execution. Resolution is `PERRY_SFW` (an explicit path) → `sfw` found by an explicit `PATH` walk that drops empty and relative entries (both resolve against the not-yet-scanned project directory; Windows `PATHEXT` is honored). The `$HOME` dev-tools rack is deliberately **not** probed — nothing in a shipped perry binary can verify that file, so preferring it would let anything that writes under `$HOME` pick the binary perry executes; the not-found message names the rack path so contributors know what to point `PERRY_SFW` at. Fail-open when sfw is absent, but never silent-open: the stderr notice prints on every run including `--json`, and the install report records the outcome under `firewall.state` (`active`/`opted-out`/`unavailable`, defaulting to `unavailable` so a forgetful path under-claims protection). `--no-firewall` opts out. The child env sets the `SFW_SHIM_ACTIVE_*` sentinels (built by iterating `Installer::ALL`, so a new installer can't ship without one) so a shimmed package manager execs the real binary instead of nesting a second proxy, and `SFW_UNKNOWN_HOST_ACTION=ignore` keeps enterprise sfw from blocking non-registry hosts. Companion to the supply-chain soak PR (#6912); notably closes the gap where the bun path bypassed the sfw shims entirely (bun is not a shimmed ecosystem).

crates/perry/src/commands/install/detect.rs

@@ -10,13 +10,30 @@ pub enum Installer {
 }
 
 impl Installer {
+    /// Every variant perry can pick. Anything that must stay in step with the
+    /// set of installers — notably the Socket Firewall shim sentinels in
+    /// `firewall::firewall_env` — iterates this instead of restating the list,
+    /// so adding a variant here is enough (and the compiler flags the
+    /// `match`es that also need updating).
+    pub const ALL: [Installer; 2] = [Installer::Bun, Installer::Npm];
+
     pub fn binary(&self) -> &'static str {
         match self {
             Installer::Bun => "bun",
             Installer::Npm => "npm",
         }
     }
 
+    /// The `SFW_SHIM_ACTIVE_*` variable that tells an sfw shim for this
+    /// package manager to exec the real binary instead of starting a second,
+    /// nested proxy inside the one perry already started.
+    pub fn shim_sentinel_env(&self) -> &'static str {
+        match self {
+            Installer::Bun => "SFW_SHIM_ACTIVE_BUN",
+            Installer::Npm => "SFW_SHIM_ACTIVE_NPM",
+        }
+    }
+
     pub fn print_banner(&self, use_color: bool) {
         let label = match self {
             Installer::Bun => "bun",