feat(research,cli,docs): state cost and risk knob units in introspect and the glossary

campaign introspect --unwired now annotates the four silently
misreadable knobs with unit/semantics sub-lines: cost_per_trade is a
price-unit numerator charged as cost/|entry−stop| in R (not a cost in
R); slip_vol_mult multiplies the per-cycle vol estimate; vol.length
smooths the estimator and does not set the stop's timescale; vol.k
scales the stop distance (the risk-unit lever). Rendered additively
via a new OpenSlot.notes field, so the sibling tests pinning the slot
hint lines verbatim stay green byte-identically.

The glossary's cost-model and risk-regime entries mirror the same
semantics inline (two-sentence convention kept), the risk entry
pointing at #262 for the timescale-matched variant.

closes #265

crates/aura-research/src/lib.rs

@@ -978,10 +978,22 @@ pub struct OpenSlot {
     pub path: String,
     /// Short human hint, e.g. "required, one of: content_id, identity_id".
     pub hint: String,
+    /// Additional unit/semantics notes rendered as indented sub-lines under
+    /// the slot's main line (#265) — additive, so the `hint` string itself
+    /// (pinned verbatim by earlier tests) never changes.
+    pub notes: Vec<String>,
 }
 
 fn open(path: impl Into<String>, hint: impl Into<String>) -> OpenSlot {
-    OpenSlot { path: path.into(), hint: hint.into() }
+    OpenSlot { path: path.into(), hint: hint.into(), notes: Vec::new() }
+}
+
+/// Like `open`, but carries additional unit/semantics notes (#265) rendered
+/// as indented sub-lines under the slot — the `hint` string stays exactly as
+/// `open` would have produced it, so sibling tests pinning `hint` verbatim
+/// are unaffected.
+fn open_with_notes(path: impl Into<String>, hint: impl Into<String>, notes: Vec<String>) -> OpenSlot {
+    OpenSlot { path: path.into(), hint: hint.into(), notes }
 }
 
 /// List the open slots of a (possibly partial) process document. Only the
@@ -1064,18 +1076,26 @@ pub fn open_slots_campaign(text: &str) -> Result<Vec<OpenSlot>, DocError> {
     // how it went undiscovered (#216). Absent, empty, or non-array = open.
     let risk_bound = v.get("risk").and_then(|r| r.as_array()).is_some_and(|a| !a.is_empty());
     if !risk_bound {
-        slots.push(open(
+        slots.push(open_with_notes(
             "risk",
             "optional, list of stop regimes { vol: { length, k } }; absent = one default regime",
+            vec![
+                "vol.length smooths the per-cycle vol estimator; it does not set the stop's timescale.".to_string(),
+                "vol.k scales the stop distance (the risk-unit lever).".to_string(),
+            ],
         ));
     }
     // The optional cost slot, mirroring the risk axis (#216's discoverability
     // lesson applied to #234): absent, empty, or non-array = open.
     let cost_bound = v.get("cost").and_then(|c| c.as_array()).is_some_and(|a| !a.is_empty());
     if !cost_bound {
-        slots.push(open(
+        slots.push(open_with_notes(
             "cost",
             "optional, list of cost components { constant: { cost_per_trade } } | { vol_slippage: { slip_vol_mult } } | { carry: { carry_per_cycle } }; absent = zero costs (net == gross)",
+            vec![
+                "constant.cost_per_trade is in price units, not R (charged per close as cost/|entry-stop| in R).".to_string(),
+                "vol_slippage.slip_vol_mult is a multiplier on the per-cycle vol estimate (charged in R likewise).".to_string(),
+            ],
         ));
     }
     match v.get("strategies").and_then(|s| s.as_array()) {
@@ -1932,13 +1952,21 @@ mod tests {
         assert_eq!(
             open_slots_campaign(CAMPAIGN_FIXTURE).unwrap(),
             vec![
-                open(
+                open_with_notes(
                     "risk",
                     "optional, list of stop regimes { vol: { length, k } }; absent = one default regime",
+                    vec![
+                        "vol.length smooths the per-cycle vol estimator; it does not set the stop's timescale.".to_string(),
+                        "vol.k scales the stop distance (the risk-unit lever).".to_string(),
+                    ],
                 ),
-                open(
+                open_with_notes(
                     "cost",
                     "optional, list of cost components { constant: { cost_per_trade } } | { vol_slippage: { slip_vol_mult } } | { carry: { carry_per_cycle } }; absent = zero costs (net == gross)",
+                    vec![
+                        "constant.cost_per_trade is in price units, not R (charged per close as cost/|entry-stop| in R).".to_string(),
+                        "vol_slippage.slip_vol_mult is a multiplier on the per-cycle vol estimate (charged in R likewise).".to_string(),
+                    ],
                 ),
             ]
         );
@@ -2012,9 +2040,13 @@ mod tests {
         assert_ne!(with_risk, CAMPAIGN_FIXTURE, "replacen must match the fixture's seed field");
         assert_eq!(
             open_slots_campaign(&with_risk).unwrap(),
-            vec![open(
+            vec![open_with_notes(
                 "cost",
                 "optional, list of cost components { constant: { cost_per_trade } } | { vol_slippage: { slip_vol_mult } } | { carry: { carry_per_cycle } }; absent = zero costs (net == gross)",
+                vec![
+                    "constant.cost_per_trade is in price units, not R (charged per close as cost/|entry-stop| in R).".to_string(),
+                    "vol_slippage.slip_vol_mult is a multiplier on the per-cycle vol estimate (charged in R likewise).".to_string(),
+                ],
             )]
         );
         let with_both = CAMPAIGN_FIXTURE.replacen(