fix(security): land the 2026-07 audit fixes — SSRF guards, roster lane, SYSTEM path hygiene

The low/medium findings from the July host+Windows security review, as
implemented in the audit session's working tree:

- Webhooks and library-art fetches refuse loopback/link-local/metadata
  targets and no longer follow redirects (SSRF pivots from the privileged
  host process).
- The paired-client rosters (/clients, /native/clients) move off the
  streaming-client auth lane — one paired device could enumerate every other
  device's name + fingerprint; only the bearer/loopback console keeps them.
- Device-name sanitizing extends to bidi/format control characters
  (spoofable rendering) via the shared native_pairing::is_spoofy_char;
  stream-marker quoting uses the same set.
- The SYSTEM service resolves powershell by its full System32 path —
  CreateProcess checks the launching EXE's own directory first, so a planted
  powershell.exe beside the host binary would have run as SYSTEM.
- The pf-vdisplay driver's opt-in file log moves from world-writable
  C:\Users\Public to WUDFHost's own temp dir.
- GameStream pairing sessions are single-use (removed whatever the outcome).
- Uninstall also removes the pf_mouse driver-store entry (rider from the
  virtual-HID-mouse work).
- openapi.json regenerated (hardened-config-dir doc wording).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

crates/punktfunk-host/src/mgmt/auth.rs

@@ -105,8 +105,11 @@ pub(crate) fn cert_may_access(method: &Method, path: &str) -> bool {
             "/api/v1/host"
                 | "/api/v1/compositors"
                 | "/api/v1/status"
-                | "/api/v1/clients"
-                | "/api/v1/native/clients"
+                // The paired-client ROSTERS (`/clients`, `/native/clients`) are deliberately NOT on
+                // this lane — they expose every OTHER paired device's name + fingerprint, which one
+                // paired streaming client must not be able to enumerate. Only the bearer/loopback
+                // console needs them, and no first-party client calls them (security-review 2026-07-17).
+                //
                 // The native clients browse the game library with their cert (no bearer token); the
                 // library MUTATIONS (POST/PUT/DELETE /library/custom) stay token-only via the exact
                 // GET-path match above.