chore(release): bump workspace version to 0.16.0

MINOR, not the 0.15.1 originally planned: the 24 commits since v0.15.0 carry 7
features, and they are not incidental — they change the plugin runner's privilege
model. It stops holding the console's full-admin token (scoped plugin-token lane),
the Windows runner drops from SYSTEM to LocalService, public-registry plugin
installs are gated behind an explicit flag, and the systemd user unit is sandboxed.
Operators have workflow-visible changes to absorb (a plugin genuinely needing the
admin surface must now set PUNKTFUNK_MGMT_TOKEN; installing outside the @punktfunk
scope needs --allow-public-registry). A patch label would understate all of that,
and sdk-publish pushes this version straight to consumers.

The other 12 fixes are largely the pf-encode/zerocopy/capture/inject quality sweep
landing: teardown deadlocks, error-path leaks, a GL->CUDA copy race, an odd-height
NV12 overrun, a cursor-meta OOB read, plus the two loss-recovery gaps 0.15.0 left
open (Vulkan Video never got the LTR taint sweep; QSV's sweep skipped its modal
single-swept-slot case).

`WIRE_VERSION` stays 2 and the driver protocol stays v4 — pairings, clients and
installed drivers keep working. The C ABI moves 8 -> 9 (PunktfunkFrame grows
`received_ns`, so receipt is stamped at the session boundary rather than at the
embedder's pull); the gitignored Apple xcframework needs a rebuild for that to
reach the Apple clients. No OpenAPI path changes (45 before and after) — the new
plugin-token lane is auth-layer only — so api/openapi.json moves info.version only.

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

api/openapi.json

@@ -10,7 +10,7 @@
       "name": "MIT OR Apache-2.0",
       "identifier": "MIT OR Apache-2.0"
     },
-    "version": "0.15.0"
+    "version": "0.16.0"
   },
   "paths": {
     "/api/v1/clients": {