refactor(host/W6.1): extract the config() global into the pf-host-config leaf crate

Third de-coupling for the host crate carve (plan §W6.1 leaf). HostConfig + the config()
OnceLock (config.rs, pure std, zero deps) move to a new pf-host-config leaf so every
subsystem crate (pf-encode/pf-capture/pf-vdisplay/pf-gpu) can read process config WITHOUT
depending on the orchestrator. 34 crate::config::config() call sites across 19 files
repoint to pf_host_config::config(). thread_qos stays in the host for now (it calls
session_tuning::on_hot_thread — its own leaf-ification rides the encode carve).

Granular-crate decision (supersedes the plan's single pf-media): split capture/encode/
vdisplay into separate crates rather than one broad crate — the capture↔encode cycle is
broken by a shared frame-types leaf, and vdisplay→encode (can_open_another_session) is a
legal one-way edge since encode never references vdisplay.

Verified: Linux (home-worker-5) clippy -p pf-host-config -p punktfunk-host --all-targets
-D warnings; Windows (192.168.1.158) clippy --features nvenc,amf-qsv --all-targets green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/pf-host-config/Cargo.toml

@@ -0,0 +1,12 @@
+# The process-wide host configuration global (HostConfig + the config() OnceLock), extracted into a
+# leaf crate so every subsystem crate (pf-encode, pf-capture, pf-vdisplay, pf-gpu) can read config
+# WITHOUT depending on the orchestrator (plan §W6 — config parked above its consumers). Pure std.
+[package]
+name = "pf-host-config"
+version = "0.12.0"
+edition = "2021"
+license = "MIT OR Apache-2.0"
+description = "Process-wide punktfunk host configuration (env-parsed HostConfig behind a OnceLock)."
+publish = false
+
+[dependencies]