Make .fkst/env.example describe what it can actually do

.fkst/env.example

@@ -1,43 +1,27 @@
-# Copy this file to .fkst/env (gitignored) and fill in your local paths:
+# Copy this file to .fkst/env (gitignored):
+#
 #   cp .fkst/env.example .fkst/env
-# Loaded by scripts/run.sh (and the commands in README.md).
+#
+# Only the BIN= line is read from it. scripts/bin_bootstrap.sh greps this file for
+# `^BIN=` and ignores every other line, so no other setting placed here has any
+# effect.
 
 # Path to the fkst-framework binary built from the fkst-substrate repo.
 # Typically the sibling checkout: <parent>/fkst-substrate/target/debug/fkst-framework
+# Resolution order is: $BIN, then this line, then PATH, then ../fkst-substrate,
+# and finally a build of the revision pinned in .fkst/substrate-ref.
 BIN=/path/to/fkst-substrate/target/debug/fkst-framework
 
-# Set to skip local freshness builds before test/run/supervise.
-# FKST_NO_AUTOBUILD=1
-
-# --- Optional host config (for real runs; the integration test sets its own) ---
-# FKST_GITHUB_REPO=owner/repo
-# FKST_GITHUB_WRITE=1
-# FKST_GITHUB_WRITE is the only write posture switch:
-# unset/anything else = dry-run; 1 = autonomous real writes.
-
-# github-devloop autonomous dogfood (per-device topology): develop -> integration-<device> -> rollup -> dev
-# FKST_GITHUB_REPO=ChronoAIProject/fkst-packages
-# FKST_GITHUB_WRITE=1
-# FKST_GITHUB_BOT_LOGIN=<this device's bot login, e.g. ElonSG>   # <device> = this login
-# FKST_GITHUB_PROXY_POLL_LABEL_PREFIX=fkst-dev:                   # lifecycle-managed label prefix for github-proxy replay filtering
-# FKST_DEVLOOP_UPSTREAM_BRANCH=dev
-# FKST_DEVLOOP_INTEGRATION_BRANCH=integration-<device>           # one per machine, e.g. integration-ElonSG
-# FKST_DEVLOOP_ROLLUP_MERGE=auto
-
-# --- Runtime roots ---
-# FKST_RUNTIME_ROOT is best-effort scratch for local worktrees, locks, logs,
-# cache, and once marks. It can be temporary for one-shot dogfood runs.
-# FKST_DURABLE_ROOT is the durable redb delivery store for supervise/reliable
-# delivery. Real supervise requires it once reliable subscriptions exist
-# (default). Keep it on a separate path from FKST_RUNTIME_ROOT; do not point both
-# at the same disposable scratch directory.
-# scripts/run.sh defaults these to .fkst/run/runtime and .fkst/run/durable when unset.
-# FKST_RUNTIME_ROOT=/path/to/scratch
-# FKST_DURABLE_ROOT=/path/to/durable
-
-# --- Shared external-command rate pools ---
-# FKST_RATE_POOL_ROOT must be host-stable and shared by every supervise instance
-# that spends the same external API budget. The packages tag all gh traffic with
-# the named pool "gh"; host posture owns its size via FKST_RATE_POOL_GH.
-# FKST_RATE_POOL_ROOT=/path/to/host-stable/rate-pools
-# FKST_RATE_POOL_GH=50,50
+# --- Everything else is an environment variable, not a line in this file ---
+#
+# Export FKST_NO_AUTOBUILD=1 to skip the freshness build before test and run.
+# scripts/run.sh defaults FKST_RUNTIME_ROOT and FKST_DURABLE_ROOT to
+# .fkst/run/runtime and .fkst/run/durable when they are unset.
+#
+# The FKST_GITHUB_* and FKST_DEVLOOP_* variables are host posture, and this
+# repository no longer supplies them. A deployment declares them in
+# fkst-deployments and fkst-ops derives the supervise environment from that
+# declaration. Setting them here would do nothing twice over: this file is not
+# sourced, and scripts/run.sh unsets them anyway -- `run` clears
+# FKST_GITHUB_WRITE so a single department run cannot mutate GitHub, and the
+# test path clears the whole hermetic set so tests cannot read host posture.