#2 (framework): bi-directional / service-function engine

Profile-defined UDS action sequences, run safely -- the framework for #2 (real
per-vehicle actuator tests/resets are follow-on, added as verified profile data).

- obdcore/actions.py: Action model + run_action() executing session (Mode 10) ->
  security (Mode 27 seed->key) -> command steps (2F/31/11/3E/... any hex) with
  positive/negative response checks. Security KEY algorithms are per-vehicle
  secrets and NOT bundled -- only trivial transforms (xor-ff/invert/add-ff)
  known; an action naming an unknown algorithm is BLOCKED (fails safe). Never
  synthesizes bytes -- runs only what the profile defines. validate_action()
  rejects malformed hex at load.
- profile.py: load/save an actions[] block; ElmLink/MockLink read_raw(hex).
- GUI: Diagnostics -> Service & Bi-directional dialog -- lists the profile's
  actions with risk badges; caution/danger gated behind a warning confirmation.
- generic-obd2: two safe STANDARD actions (Tester-Present ping; ECU-Reset,
  caution + engine-off warning). PROFILE_SPEC.md documents the actions schema
  + safety rules.
- tests/test_actions.py: runner, session+reset, security handshake, unknown-algo
  block, hex validation, profile load. All 5 suites pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016yT89n4zR4qbrySoSiEyZs

obdcore/link.py

@@ -175,6 +175,11 @@ class ElmLink:
         except ValueError:
             return None
 
+    def read_raw(self, hexcmd, timeout=2.0):
+        """Send an arbitrary hex command and return the flattened response
+        bytes (for bi-directional actions / service routines)."""
+        return self._bytes(self.cmd(hexcmd, timeout=timeout))
+
     # -- DTCs --
     def read_dtcs(self, mode, svc, timeout=5.0):
         lines = self.cmd(mode, timeout=timeout)