feat(wait): add structured wait endpoint

docs/API.md

@@ -277,6 +277,80 @@ Notes:
 - If `wait_for_window=true`, the server polls for a matching window and returns `window_found`.
 - `dry_run=true` returns the resolved argv/cwd without launching.
 
+## `POST /wait`
+
+Wait on a structured UI condition instead of guessing sleep durations.
+
+Query params:
+
+- `screen` (int, default `0`) - used for text and visual waits
+
+### Wait for text to appear
+
+```json
+{
+  "condition": {
+    "kind": "text",
+    "mode": "screen",
+    "text": "Scan complete",
+    "match": "contains",
+    "present": true,
+    "language_hint": "eng",
+    "min_confidence": 0.4
+  },
+  "timeout_ms": 15000,
+  "poll_interval_ms": 400
+}
+```
+
+### Wait for a window state
+
+```json
+{
+  "condition": {
+    "kind": "window",
+    "title_contains": "WinDirStat",
+    "visible_only": true,
+    "state": "focused"
+  },
+  "timeout_ms": 5000,
+  "poll_interval_ms": 200
+}
+```
+
+Window states:
+- `exists`
+- `focused`
+- `closed`
+
+### Wait for visual change or stability
+
+```json
+{
+  "condition": {
+    "kind": "visual",
+    "state": "stable",
+    "region_x": 0,
+    "region_y": 0,
+    "region_width": 1920,
+    "region_height": 1080,
+    "diff_threshold": 0.005,
+    "stable_for_ms": 1000
+  },
+  "timeout_ms": 12000,
+  "poll_interval_ms": 300
+}
+```
+
+Visual states:
+- `change` — succeeds when the average pixel diff crosses `diff_threshold`
+- `stable` — succeeds when the diff stays at or below `diff_threshold` for `stable_for_ms`
+
+Notes:
+- Text waits reuse the OCR pipeline and return matching OCR blocks on success.
+- Window waits build on the structured window discovery endpoint.
+- Visual waits compare repeated captures of either the full selected display or an explicit region.
+
 ## `POST /ocr`
 
 Extract visible text from either a full screenshot, a region crop, or caller-provided image bytes.