align(4909d): every rule arm that annotates reads one bar, kb_rule_threshold at 0.70

prompt_rule, pre_tool_rule and write_path_rule now share one settings key,
RULE_FLOOR_KEY = "kb_rule_threshold", default 0.70. The reply backstop keeps
its own 0.80, because there the floor is a stop bar. Moving the shared floor
through tune_retrieval or the Settings form records a tuning event on every
surface that reads it (set_dial, via retrieval_surfaces.sharing_floor), and
the result names the surfaces it carried as `moved_with`. Settings shows one
"Standing-rule confidence threshold" control where it showed three.

Operator ruling (2026-10-05): one shared bar for the rule arms, "especially
since we're only taking the first x number of them" -- the budget limits
what is shown; the bar only decides what is worth ranking. Kept a dial.

Why 0.70, from records read rather than percentiles:
- write_path_rule near-misses at 0.7199-0.72 were all false positives
  (rule 149 against a Lidarr comment, 157 against a retention Svelte file,
  121 against an Archives restore, 164 against a config test, 131 against a
  Go package), so the old 0.72 was not hiding real hits -- but the band does
  noise control on this arm, so dropping 0.02 costs little.
- prompt_rule: the operator set 0.70 by hand on 2026-09-18, after a 0.60
  experiment admitted junk and was reverted. 0.70 is the number with a human
  decision behind it.
- pre_tool_rule lines near 0.68 this session were mostly noise; rising to
  0.70 trims them, and the band still narrows what clears.

Retired keys: kb_promptrule_threshold, kb_toolrule_threshold and
kb_rulehint_threshold are no longer read. Rows an install stored under them
stay in the settings table, inert. On this instance the effective bars move
pre_tool_rule 0.68 -> 0.70, write_path_rule 0.72 -> 0.70, prompt_rule stays
0.70; record_release_defaults writes those per-surface release rows on boot,
so the telemetry shift has an event to explain it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/grimoire/services/retrieval_surfaces.py

@@ -110,6 +110,9 @@ def dial_for_key(key: str) -> tuple[str, str] | None:
 
     Derived rather than listed so a seventh surface is covered the moment it is
     added here, which is the only way this stays true.
+
+    A floor key several surfaces share resolves to the first of them;
+    `set_dial` records the move on every surface in `sharing_floor`.
     """
     for surface in SURFACES.values():
         if key == surface.floor_key:
@@ -119,6 +122,16 @@ def dial_for_key(key: str) -> tuple[str, str] | None:
     return None
 
 
+def sharing_floor(name: str) -> list[str]:
+    """Every surface that reads the same floor key as `name`, itself included.
+
+    The rule arms share one bar, so moving one surface's floor moves its
+    siblings, and each of them needs the event that says so.
+    """
+    key = get_surface(name).floor_key
+    return [n for n, s in SURFACES.items() if s.floor_key == key]
+
+
 async def floor_for(user_id: int, name: str) -> float:
     """This install's current floor for a surface, clamped to [0, 1]."""
     s = get_surface(name)