test(testing): raise waitForText poll default 5000->10000ms to de-flake render tests

The vitest gate flaked a 2nd time — screenshot.test.ts "preserves 256-color
codes" timed out after 5000ms waiting for ORANGE. #116 raised VITEST's
testTimeout (15000ms), but the real 5000ms is waitForText's OWN internal poll
timeout (src/testing/session.ts), which #116 never touched — so terminal render
under CI load still tripped it. Raise the waitForText/waitForAbsent/waitFor
default to 10000ms, matching the explicit 10000-15000ms render-heavy tests
already pass (scrollback-fidelity.test.ts) and staying under screenshot's
15000ms vitest testTimeout. Only affects failure/slow-wait latency; a matching
wait returns immediately.

Folded into this PR so it fixes BOTH required-gate flakes (parity teardown
ENOTEMPTY + screenshot render timeout) and one CI run validates both.

Author: myobie

src/testing/session.ts

@@ -287,8 +287,17 @@ export class Session {
 
   // ── Waiting ──
 
+  // Default poll-wait budget. Terminal render under CI load routinely exceeds
+  // the old 5000ms — it caused two screenshot render flakes (true-color, then
+  // 256-color) that false-red the required vitest gate. 10000ms matches the
+  // explicit timeouts render-heavy tests already pass (see
+  // scrollback-fidelity.test.ts) and stays under screenshot.test.ts's 15000ms
+  // vitest testTimeout, so a slow wait fails HERE with the useful "waiting for
+  // X" message rather than as a blunt vitest test-timeout. Only affects
+  // failure/slow-wait latency; a wait that matches returns immediately.
+
   /** Poll until the terminal contains the given text. Returns the matching screenshot. */
-  async waitForText(text: string, timeoutMs = 5000): Promise<Screenshot> {
+  async waitForText(text: string, timeoutMs = 10000): Promise<Screenshot> {
     const start = Date.now();
     while (Date.now() - start < timeoutMs) {
       await new Promise((r) => setTimeout(r, 50));
@@ -302,7 +311,7 @@ export class Session {
   }
 
   /** Poll until the terminal no longer contains the given text. */
-  async waitForAbsent(text: string, timeoutMs = 5000): Promise<Screenshot> {
+  async waitForAbsent(text: string, timeoutMs = 10000): Promise<Screenshot> {
     const start = Date.now();
     while (Date.now() - start < timeoutMs) {
       await new Promise((r) => setTimeout(r, 50));
@@ -318,7 +327,7 @@ export class Session {
   /** Poll until a custom predicate returns true. The `description` is used in timeout error messages. */
   async waitFor(
     predicate: (ss: Screenshot) => boolean,
-    timeoutMs = 5000,
+    timeoutMs = 10000,
     description = "predicate"
   ): Promise<Screenshot> {
     const start = Date.now();