fix(update): point the apply guidance at the installer, not felis setup (#54)

On a completed install 'felis setup' never re-runs the installer: its host-bootstrap phase only runs while an install marker is missing, so it opens the config console and moves no component. Live on the audit box, a clean 'felis setup' run left /opt/felis/velocity/velocity.jar's mtime and hash untouched while an installer re-run logged 'resolving the newest Velocity 3.5.1 build'. The 'felis update' guidance was wrong three ways accordingly: 'run: sudo felis setup' for panel/velocity/plugins, the 'felis setup is idempotent and re-runs the installer' trailer, and the felis-api-only exception block, whose scoping taught the same false model for velocity.

Point every planner-backed selector at the tested path -- re-running the installer (the README's install one-liner) -- and replace the scoped caveat with one trailer: the channel is not persisted (pass FELIS_VERSION_BOOTSTRAP=dev on a host that tracks main), the private repo's one-liner needs the README's token'd form, and 'felis setup is not this path'. troubleshooting.md SS15 drops the same false alternative and gains the channel caveat.

Gates: gofmt, go vet, go test ./..., deploy/bootstrap_test.sh all clean. Green live (v0.0.0+fix54 installed to /usr/local/bin over the fix52 backup, sha 0bd49467...): --panel and --velocity print the installer one-liner plus the single trailer, --mc stays command-free, --all prints the trailer once.

docs/troubleshooting.md

@@ -840,9 +840,11 @@ disk/memory thresholds, and the kubelet `DiskPressure` condition.
 ## 15. Control-plane upgrades, and rolling back a bad one
 
 There is no in-place updater: an upgrade is re-running the installer
-(`curl -fsSL <installer URL> | sudo bash`, or `sudo felis setup`), which
-rebuilds/re-imports the image and re-applies the bundle. Two properties of the
-control plane matter when you do:
+(`curl -fsSL <installer URL> | sudo bash`), which rebuilds/re-imports the image
+and re-applies the bundle. (`sudo felis setup` is not this path; on a completed
+install it only opens the config console.) The channel is not persisted across
+the re-run, so pass `FELIS_VERSION_BOOTSTRAP=dev` on a host that tracks main.
+Two properties of the control plane matter when you do:
 
 - Both Deployments use strategy **Recreate** (single replica, no leader election:
   two overlapping instances would fight over the same cluster). An upgrade takes