docs+scripts: TASK-E parts 4-7 - operator one-pager, rulings, hub build.sh adoption

PROMPT-TEMPLATE: standard 'For the operator' plain-language section, mandatory
for M+ tasks and anything with a STOP.

ROADMAP rulings (operator, 2026-07-21): R-25b full-teardown cascade with three
acks + typed name (M-sized, spec to follow, no longer blocks R-3); R-11 channel
= direct Messenger, doc is the architect's; R-42 option (a), sidecars follow the
app; R-17 delete the archive - spike-lite found NO tooling verb targets it, so
it is an operator console action; R-4 complete (freemail.hu verified).
R-55 + R-41 slice 1 marked shipped; new R-56 (app difficulty classification -
the constructive half of the glance ruling).

scripts/build-hub.sh v1.23.0: the hub build script was outside any repo. Adopted
verbatim + versioned; the build-dir path is now a symlink to it.

felhom-testing skill: the ~1/5 recovery-code 'known flake' is retired - it was a
real defect the test was correctly detecting.

documentation/PROMPT-TEMPLATE.md

@@ -24,6 +24,38 @@
 
 ---
 
+## For the operator — what this fixes, in one page (plain language)
+
+<!--
+  MANDATORY for any M+ task and for any task carrying a STOP. Optional but encouraged below that.
+  Precedent: TASK-B, TASK-C and TASK-D shipped with this section and it is why those runs needed no
+  mid-flight explanation; TASK-E made it a standard block.
+
+  WHO IT IS FOR: a technical-but-not-in-the-code reader — someone who runs the business and the
+  hardware, knows what the components are, and has not read the file you are about to change.
+
+  IT MUST SAY, in this order:
+    1. WHAT BREAKS TODAY — the observable symptom, not the code defect. "Your Stop is silently
+       undone on a reboot", not "shouldRecreateOnBoot ignores container state".
+    2. WHAT CHANGES — the new behaviour, in the same observable terms.
+    3. WHAT THE OPERATOR WILL BE ASKED TO DO — every STOP, every ruling needed, every physical
+       action (flash this, press that, confirm this), and anything that is HUMAN-only. If the answer
+       is "nothing", say "nothing".
+    4. WHAT IS NOT AFFECTED — especially for anything touching customer data, credentials or
+       recovery. "Existing codes still work" belongs here.
+
+  RULES:
+    - No jargon the ROADMAP row doesn't already explain. If a term must be introduced, define it in
+      the sentence that uses it.
+    - No file paths, no function names, no version numbers except the ones the operator acts on.
+    - One page. If it does not fit, the task is probably two tasks.
+    - Write it LAST, after the parts are settled, but place it HERE — it is what gets read first.
+    - It is a summary, never the spec: it must not be the only place a requirement appears, or CC
+      will implement from prose. Everything here is restated precisely in §0 onward.
+-->
+
+---
+
 ## 0. Task class & scope
 
 <!-- Pick ONE primary class. It sets which sections are mandatory. -->