A guard pins the wording of the ios-app placement paragraph, and reads the file instead of the section #2732

A guard in tests/test_prompt_templates.py pins two whole sentences about a template document, so
rewording the document turns it red even when the rule it states is unchanged — and the message it
prints then tells a reader that the rule is gone.

What it does today

tests/test_prompt_templates.py holds

_IOS_APP_PLACEMENT_CLAIMS = ("top level is honoured too", "`config:` wins")

and one test asserts both strings are substrings of emrg/server/ios_app_prompt.md. That document
states the extra_prompt placement rule in the bullet under §0.1.

Measured, both directions, on the current master:

The second row is the defect this issue is about: a paragraph is prose, and rounds rewrite prose for
meaning. A guard whose message says a sentence is gone must fail only when the property is gone, not
when the words change.

The third row is the same leg failing the other way: it reads the whole file, so any unrelated
mention anywhere satisfies it while its message claims to speak about "the paragraph".

Why it is not a strict test

The paragraph's subject is a mechanism that is already pinned by behaviour, not prose: the four
tests above this block in the same file drive the real prompt builder and assert that a top-level
extra_prompt reaches every builtin template, that a config copy still reaches it, that neither
position renders nothing, and that a record carrying both renders the config copy and warns,
naming the ignored copy with its size. Those four tests are the property; the sentence pin adds no
discrimination they lack, and costs a false red every time the prose is edited.

What the fix must satisfy

• A reword of the §0.1 bullet that keeps both halves of the mechanism stays green.
• Dropping either half — the top-level fallback renders, or the config copy is the canonical home
  that wins — fails, naming the half that went missing.
• Deleting the bullet instead of correcting it fails, so the paragraph cannot be removed in
  silence.
• Moving the bullet out of §0.1 fails: the reading is about that section, not about the file.
• The reading is a keyword set anchored on the two positions the rule must name, never a whole
  sentence; the direction of the claim is a review duty, and the test says so in its own docstring
  rather than implying it measured it.

Scope

One test in tests/test_prompt_templates.py and the constant beside it. No change to
emrg/server/ios_app_prompt.md is needed: the document's current wording is correct.