chore: push all design docs, V2 plan specs, and current working state

Includes AirPlan design documents, AircOding-alpha1-plan, AirPlanV2,
AirPlan-ParaV2, AirPlan-Para V1 reference docs, and all working code
changes across packages.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

AirPlan/docs/spec/AirPlanV2/lib/air_runtime/lock.py

@@ -0,0 +1,44 @@
+"""
+文件级并发控制 — 解决 V1 P0-4 零并发控制问题。
+基于 fcntl.flock 的进程级文件锁，超时自动释放。
+"""
+
+from __future__ import annotations
+
+import fcntl
+import os
+import time
+from pathlib import Path
+
+
+class FileLock:
+    """基于 fcntl.flock(LOCK_EX | LOCK_NB) 的进程级文件锁"""
+
+    def __init__(self, path: Path, timeout: float = 10.0):
+        self._path = path.with_suffix(path.suffix + ".lock") if not path.suffix.endswith(".lock") else path
+        self._timeout = timeout
+        self._fd: int | None = None
+
+    def __enter__(self) -> FileLock:
+        self._fd = os.open(self._path, os.O_CREAT | os.O_RDWR)
+        deadline = time.monotonic() + self._timeout
+        while True:
+            try:
+                fcntl.flock(self._fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
+                return self
+            except OSError:
+                if time.monotonic() >= deadline:
+                    os.close(self._fd)
+                    self._fd = None
+                    raise TimeoutError(f"lock timeout after {self._timeout}s: {self._path}")
+                time.sleep(0.1)
+
+    def __exit__(self, *exc) -> None:
+        if self._fd is not None:
+            fcntl.flock(self._fd, fcntl.LOCK_UN)
+            os.close(self._fd)
+            self._fd = None
+
+    @property
+    def path(self) -> Path:
+        return self._path