refactor: master 沿用 release 轨道名，develop 用 develop，feature 用 feature

上一版把 master 的轨道也改名成 master，会把历史构建号搬到新键上。
改为 master/main 继续用现有的 release 轨（build_map 原地保留），
只有 develop 等其它上架分支新建以分支名命名的轨道并复制一份构建号。

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BJaZ913U5GVdTkYHiRpvDU

tests/test_build_service.py

@@ -344,7 +344,7 @@ async def test_generate_config_uses_saved_version(tmp_path, log_streamer):
     task.obfuscation = False
     task.branch = "master"
 
-    mock_config = _versions_config({"master": _release("3.0.1"), "feature": _feature("9.9.9")})
+    mock_config = _versions_config({"release": _release("3.0.1"), "feature": _feature("9.9.9")})
 
     with patch("backend.routers.config.load_config", return_value=mock_config):
         result = await generate_config("t1", task, build_dir)
@@ -363,7 +363,7 @@ async def test_generate_config_appstore_increments_per_version(tmp_path, log_str
 
     # 2.195.0 已打到 .5，切到 2.196.0 后又回退到 2.195.0
     mock_config = _versions_config({
-        "master": _release("2.195.0", {"2.195.0": 5, "2.196.0": 3}),
+        "release": _release("2.195.0", {"2.195.0": 5, "2.196.0": 3}),
         "feature": _feature("2.195.0"),
     })
 
@@ -372,7 +372,7 @@ async def test_generate_config_appstore_increments_per_version(tmp_path, log_str
         result = await generate_config("t1", task, build_dir)
 
     # 从 2.195.0 自身的 5 继续到 6，不受 2.196.0 影响，也不撞已传的 .5
-    release_map = mock_config["versions"]["tracks"]["master"]["build_map"]
+    release_map = mock_config["versions"]["tracks"]["release"]["build_map"]
     assert result["BUILD_VERSION"] == "2.195.0.6"
     assert release_map["2.195.0"] == 6
     assert release_map["2.196.0"] == 3
@@ -388,7 +388,7 @@ async def test_generate_config_release_branches_are_independent(tmp_path, log_st
                      obfuscation=False, branch="develop")
 
     mock_config = _versions_config({
-        "master": _release("2.195.0", {"2.195.0": 5}),
+        "release": _release("2.195.0", {"2.195.0": 5}),      # master
         "develop": _release("2.196.0", {"2.196.0": 1}),
         "feature": _feature("2.100.0"),
     })
@@ -399,8 +399,8 @@ async def test_generate_config_release_branches_are_independent(tmp_path, log_st
 
     assert result["VERSION"] == "2.196.0"
     assert result["BUILD_VERSION"] == "2.196.0.2"
-    # master 轨完全不受影响
-    assert mock_config["versions"]["tracks"]["master"]["build_map"] == {"2.195.0": 5}
+    # master 的 release 轨完全不受影响
+    assert mock_config["versions"]["tracks"]["release"]["build_map"] == {"2.195.0": 5}
 
 
 async def test_generate_config_build_no_skips_other_release_track(tmp_path, log_streamer):
@@ -412,7 +412,7 @@ async def test_generate_config_build_no_skips_other_release_track(tmp_path, log_
                      obfuscation=False, branch="develop")
 
     mock_config = _versions_config({
-        "master": _release("2.196.0", {"2.196.0": 7}),
+        "release": _release("2.196.0", {"2.196.0": 7}),      # master
         "develop": _release("2.196.0", {"2.196.0": 2}),
         "feature": _feature("2.100.0"),
     })
@@ -434,7 +434,7 @@ async def test_generate_config_feature_branch_never_increments(tmp_path, log_str
                      obfuscation=False, branch="feature/login")
 
     mock_config = _versions_config({
-        "master": _release("2.195.0", {"2.195.0": 5}),
+        "release": _release("2.195.0", {"2.195.0": 5}),
         "feature": _feature("2.100.0"),
     })
 
@@ -457,7 +457,7 @@ async def test_generate_config_branch_track_override(tmp_path, log_streamer):
                      obfuscation=False, branch="release/2.196")
 
     mock_config = _versions_config({
-        "master": _release("2.196.0"),
+        "release": _release("2.196.0"),
         "feature": _feature("2.100.0"),
     })
     mock_config["branch_track"] = {"release/2.196": "feature"}