refactor(src): narrow exception types in Phase 7 batch (8 sites across 7 files)

Migrates the 8 try/except sites in Infrastructure + Hook + Utility
files by narrowing the exception types from broad 'except Exception'
to specific stdlib/domain exceptions.

Files and sites:
1. src/api_hooks.py:453 (HookHandler.do_GET error response)
   except Exception -> except (OSError, ValueError)
2. src/api_hooks.py:826 (HookHandler.do_POST error response)
   except Exception -> except (OSError, ValueError)
3. src/api_hooks.py:916 (websocket connection cleanup)
   except Exception -> except (OSError, ValueError)
4. src/file_cache.py:84 (path mtime stat)
   except Exception -> except (OSError, ValueError)
5. src/orchestrator_pm.py:37 (track metadata.json read)
   except Exception -> except (OSError, json.JSONDecodeError, UnicodeDecodeError)
6. src/orchestrator_pm.py:49 (track spec.md read)
   except Exception -> except (OSError, UnicodeDecodeError)
7. src/outline_tool.py:67 (ast.unparse node.returns)
   except Exception -> except (ValueError, TypeError)
8. src/outline_tool.py:90 (ast.unparse ImGui context)
   except Exception -> except (ValueError, TypeError, AttributeError)
9. src/shell_runner.py:99 (subprocess cleanup on error)
   except Exception -> except (OSError, subprocess.SubprocessError)
10. src/summarize.py:187 (summarise_file fallback)
    except Exception -> except (OSError, ValueError, TypeError, AttributeError)
11. src/summarize.py:191 (summarise_file outer)
    except Exception -> except (OSError, ValueError, TypeError)

Decisions:
- src/api_hook_client.py: 0 violations; 2 compliant sites; no migration
- src/hot_reloader.py:58 - kept except Exception (module reload can
  raise any exception; test fixture uses generic Exception)
- src/api_hooks.py:938-941 - RETHROW (keep as-is; cascading if changed)

Tests verified:
- tests/test_outline_tool.py (3 tests) PASS
- tests/test_hot_reloader.py (8 tests) PASS
- tests/test_hot_reload_integration.py (13 tests) PASS

src/outline_tool.py

@@ -87,7 +87,7 @@ class CodeOutliner:
     if getattr(node, "returns", None):
      try:
       returns = f" -> {ast.unparse(node.returns)}"
-     except Exception:
+     except (ValueError, TypeError):
       pass
     output.append(f"{'  ' * indent}{prefix} {node.name}{returns} (Lines {start_line}-{end_line})")
     doc = get_docstring(node)
@@ -106,7 +106,7 @@ class CodeOutliner:
        output.append(f"{'  ' * indent}[ImGui Scope] {ctx_str} (Lines {start_line}-{end_line})")
        is_imgui = True
        break
-    except Exception:
+    except (ValueError, TypeError, AttributeError):
      pass
     for item in node.body:
      walk(item, indent + 1 if is_imgui else indent)