docs(design): trim shipped plans, consolidate cluster, add index

Much of design/ described work that has since shipped. Trim each doc to
its durable rationale + still-open items (the code is the source of truth
for shipped detail; git history holds the full originals).

- Shipped plans -> status stubs: stats-capture, gamestream-host-plan,
  apple-stage2-presenter, windows-service.
- Trimmed completed-out / open-kept: implementation-plan, hdr-pipeline,
  host-latency, gpu-contention (fixed stale status table), game-library,
  linux-setup (fixed m0->spike + stale zero-copy claim),
  session-aware-host-followups, windows-client-bootstrap,
  windows-dualsense-{scoping,game-detection}, windows-virtual-display,
  security-review (per-finding status table; #12 still open),
  apollo-comparison (shipped backlog collapsed to one-liners).
- Windows-host cluster consolidated: windows-host.md -> redirect into
  windows-host-rewrite.md (whose stale scorecard is corrected -- goal1 is
  merged, M4 done); windows-secure-desktop.md archived (now a fallback
  behind IDD-push primary).
- Kept evergreen: ci.md, gamescope-multiuser.md, windows-build-and-packaging.md.
- New design/README.md: per-doc status table + consolidated open-items
  roll-up so nothing is tracked in only one buried doc.
- Repoint 5 code comments to the archived secure-desktop doc path.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/punktfunk-host/src/main.rs

@@ -35,6 +35,9 @@ mod gamestream;
 mod hdr;
 mod inject;
 #[cfg(target_os = "windows")]
+#[path = "windows/install.rs"]
+mod install;
+#[cfg(target_os = "windows")]
 #[path = "windows/interactive.rs"]
 mod interactive;
 mod library;
@@ -390,7 +393,7 @@ fn real_main() -> Result<()> {
         }
         // USER-session WGC helper (Windows two-process secure-desktop design): capture the EXISTING
         // SudoVDA via WGC + NVENC, stream AUs on stdout to the SYSTEM host. Spawned by the host
-        // (CreateProcessAsUser), not run by hand. See design/windows-secure-desktop.md.
+        // (CreateProcessAsUser), not run by hand. See design/archive/windows-secure-desktop.md.
         #[cfg(target_os = "windows")]
         Some("wgc-helper") => {
             let get = |flag: &str| {
@@ -422,6 +425,12 @@ fn real_main() -> Result<()> {
         // that launches the host into the active interactive session.
         #[cfg(target_os = "windows")]
         Some("service") => service::main(&args[1..]),
+        // Install-time work the Windows installer delegates to the exe instead of locale-parsed
+        // PowerShell *files* (the ANSI-codepage parse-break root fix; see windows/install.rs).
+        #[cfg(target_os = "windows")]
+        Some("driver") => install::driver_main(&args[1..]),
+        #[cfg(target_os = "windows")]
+        Some("web") => install::web_main(&args[1..]),
         Some("-h") | Some("--help") | Some("help") | None => {
             print_usage();
             Ok(())