refactor: drop the two store members nothing consults

`TuiModelStore.confirmSatisfied()` and `approvalFor()` had no caller
outside their own tests. The first one mattered: it answered "does the
typed text authorize this kill?" with an exact name match, while the rule
actually consulted (`confirmAccepts()` in tui-app) also accepts the
8-character id prefix a mux name carries. Two divergent answers to one
question, the stricter one unreachable and waiting to be picked up by
mistake. knip cannot see class members, so the dead-code sweep never
flagged either.

The tests they existed for now assert observable state instead, and the
approvals one got stronger on the way: it checks that a session id coming
back does not inherit the dead session's dialog, which is the invariant
`removeSession()` is actually keeping.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/tui/tui-model.ts

@@ -349,10 +349,6 @@ export class TuiModelStore implements TuiRenderModel {
     });
   }
 
-  approvalFor(sessionId: string): ApprovalItem | undefined {
-    return this.approvalsBySession.get(sessionId);
-  }
-
   sessions(): TuiSessionRow[] {
     return [...this.sessionsById.values()];
   }
@@ -440,7 +436,12 @@ export class TuiModelStore implements TuiRenderModel {
     this.touch();
   }
 
-  /** Arm the typed-name confirmation for `x` (kill). */
+  /**
+   * Arm the typed-name confirmation for `x` (kill). Whether what the user typed
+   * AUTHORIZES the kill is `confirmAccepts()` in tui-app, which owns that rule
+   * for every caller: a second copy here answered the same question differently
+   * (it refused the id prefix a mux name carries) and nothing consulted it.
+   */
   beginConfirmKill(row: TuiRow): void {
     this.confirm = {
       sessionId: row.session.sessionId,
@@ -457,11 +458,6 @@ export class TuiModelStore implements TuiRenderModel {
     this.touch();
   }
 
-  /** Does the typed text authorize the kill? Exact match on the name shown. */
-  confirmSatisfied(): boolean {
-    return this.confirm !== null && this.confirm.typed.trim() === this.confirm.name;
-  }
-
   /** Drop whatever overlay owns the keyboard and go back to the list. */
   closeOverlay(): void {
     this.confirm = null;