docs: fix review findings — residual ordinals, hypothetical IPC row, citation-rule amendments

Purge the residual task/phase ordinals review caught ((T2), (queue cut 1)
×3, T6, P-I, 'this cut' ×6 including battery-expansion finds in two
untouched notes and a workflow JSDoc); drop the 'externally logged as
Decision 21' parenthetical and rename the remaining bare decision-21
mentions; mark the gui-layering IPC bridge row as a hypothetical example;
restore the GATE_NOTICE doc-typecheck clause and the py-types 'measured'
provenance; say subprocess-backed in filesystem.md; add the picker note
path. Amend the citations note: merged-PR evidence anchors in Agent Notes
are sanctioned, and the candidate gate patterns gain the four shapes the
sweep missed. All nine touched pairs re-recorded.

packages/host/directory-picker-native/src/native-picker.ts

@@ -71,7 +71,7 @@ export async function pickNativeDirectory(
     // per-monitor-v2 DPI and abort support. koffi is a packaged dependency
     // whose availability the install guarantees, so there is no fallback
     // tier: any failure surfaces as-is (no PowerShell fallback tier; see
-    // the simplification Agent Note).
+    // .agents/notes/implemented/simplification/2026-08-04-drop-windows-powershell-picker-fallback.md).
     const pickDialog = internals.pickWin32Dialog ?? pickWin32Directory
     return await pickDialog(signal)
   }