claude-cli: pause until reset on session-limit; harden capability-set loader

- On a Claude Code session/usage limit ('resets 7:10pm'), _call_claude_cli now
  pauses IN PLACE until the stated reset time + CLAUDE_CLI_LIMIT_BUFFER_SECONDS
  (default 60s past), then retries — up to CLAUDE_CLI_LIMIT_MAX_WAITS windows.
  Parses 12-hour reset times to their next occurrence; falls back to a fixed
  wait when no time is present. Makes long unattended runs survive reset windows.
- load_library() reports invalid capability-set JSON as a clean SystemExit
  (line number + reason) instead of a traceback; fixed a trailing-comma typo in
  data/capability_sets/dx02.json.
- Docs: USAGE.md + .env.example document the claude-cli provider and its knobs.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

sales-agent/src/capabilities.py

@@ -50,11 +50,16 @@ def active_set() -> str:
 
 @lru_cache(maxsize=1)
 def load_library() -> dict:
-    if _active_set == "ALL":
-        return json.loads((config.DATA_DIR / "capabilities.json").read_text())
-    return json.loads(
-        (config.DATA_DIR / "capability_sets" / f"{_active_set}.json").read_text()
-    )
+    path = (config.DATA_DIR / "capabilities.json" if _active_set == "ALL"
+            else config.DATA_DIR / "capability_sets" / f"{_active_set}.json")
+    try:
+        lib = json.loads(path.read_text())
+    except json.JSONDecodeError as e:
+        raise SystemExit(f"Capability set '{_active_set}' has invalid JSON "
+                         f"({path.name}, line {e.lineno}): {e.msg}. Fix the file and re-run.")
+    if not lib.get("capabilities"):
+        raise SystemExit(f"Capability set '{_active_set}' ({path.name}) has no 'capabilities'.")
+    return lib
 
 
 def capability_by_id(cap_id: str) -> dict | None: