docs(adr): one rule for a reference to a formula target, and the right count of readings (improvise-cq1q.1)

Copilot found two inconsistencies in the previous push:
- clause 5 said a WHERE/IS value is an item id while Q23 said it could be a formula id.
  Clause 5 now states one rule, the id text of an ItemHandle, for an expression and a
  filter value alike, and Q23 points to it instead of restating it;
- the status header still said three readings were flagged, where Q23 lists eight.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VdfEGXA7aJ6ftMsCc9PJze

context/adr/007-stable-identities.md

@@ -8,8 +8,8 @@ user approved revision 8 on PR #210 (owner comment 5824468104, 2026-09-25 00:17:
 **Revision 9 is a proposed amendment, not yet approved.** It folds in the user's
 answers on the implementation tickets (answers 30–32) and clarifies text the
 reviews found unclear or stale (improvise-cq1q.1). It changes no earlier decision.
-It asks one new question, Q23 (a formula line's spelling), and flags three places
-where it states the ADR's own reading. ·
+It asks one new question, Q23 (a formula line's spelling), and flags eight readings
+of its own that are not user answers, listed under Q23. ·
 **Decided by:** the user; see "What the user decided" ·
 **Ticket:** improvise-sboz · **Unblocks:** improvise-fz77 ·
 **Revises:** improvise-km71's interim `FormulaId` (landed in PR #214) and
@@ -687,9 +687,13 @@ an item target's id is answer 30's. It is
     writes it. Where that display lives is also the ADR's own reading.
   - Whether one line should spell both cases this way is **Q23**, below, and so
     are how an expression refers to a target and how a `_Measure` display is quoted.
-- **The expression is over ids**, spelled through `quote::quote_name` as above.
-- **A `WHERE`/`IS` filter value is an item id**, bare or quoted (answer 3: every
-  reference is an id). The formula panel shows it as a display.
+- **The expression is over ids**, spelled through `quote::quote_name` as above. A
+  reference to a formula target is the id text of its `ItemHandle`: the item id
+  outside `_Measure`, and the formula id for a `_Measure` target.
+- **A `WHERE`/`IS` filter value follows the same rule** (answer 3: every reference
+  is an id). It is the id text of an `ItemHandle` in the filtered category, bare or
+  quoted: an item id, or a formula id when the category is `_Measure` and the value
+  names a formula target. The formula panel shows it as a display.
 - **A formula cell's `CellKey`** carries `ItemHandle::Item(<target item id>)`
   outside `_Measure`. For a `_Measure` target it carries
   `ItemHandle::FormulaTarget(<formula id>)` under `_measure` (clause 2).
@@ -1087,9 +1091,10 @@ thing in one position, and the category after `[` is what tells them apart.
   formula's `FormulaId`".
 
 Two consequences of (a) that the answer should take in, both the ADR's own reading:
-- **References to a formula target.** An expression, and a `WHERE`/`IS` value,
-  names a target outside `_Measure` by its **item id**, and a `_Measure` target by
-  its **formula id**. That follows from `ItemHandle` (clause 2).
+- **References to a formula target** are as clause 5 states them, for an expression
+  and a filter value alike: the id text of an `ItemHandle`, which is the item id
+  outside `_Measure` and the formula id for a `_Measure` target. That holds under
+  (a) and (b). Under (c) a `_Measure` target would be named by its own id instead.
 - **Quoting the target position.** A `_Measure` display in the target position can
   itself look like `Name(x)`, which would read back as a display and a formula id.
   The writer's rule that pipe-quotes such a display therefore covers a