feat(i18n): full English translation of demo-epb

Phase 2 of the English translation:

Word documents (filled, EPB-specific):
- 8 plans (PID, PM, QA, SWE, Test, Project Manual, CM, RM)
- 6 safety docs (HARA, Safety Case, FMEDA, MISRA Compliance,
  Verification Report, Tool Qualification Cppcheck)
- 2 manuals (User, Service)
- 3 audit artefacts (Review minutes, NC-001, MISRA-REC-001)
- All regenerated via pandoc from English markdown sources

Code, tests, headers:
- All file headers, struct comments, function docstrings in English
- All test names (TEST_BEGIN strings) translated
- Inline comments translated
- 46 tests still green after translation

CI workflows:
- All step names in English
- Step descriptions, comments, release notes template in English

README.md fully rewritten in English with proper guided tour.

Phase 3 (still pending): dev-process repo templates + toolstack/setup docs.

src/apply_controller.h

@@ -1,6 +1,6 @@
 /**
  * @file apply_controller.h
- * @brief Apply/Hold/Release-Steuerung der EPB.
+ * @brief Apply/Hold/Release control of the EPB.
  *
  * @arch SWA-002
  * @reqs SWE-001 SWE-002 SWE-003 SWE-004
@@ -23,14 +23,14 @@ typedef struct {
     uint16_t     right_force_n;
 } ApplyInputs;
 
-#define APPLY_TARGET_FORCE_N   12000U  /* Ziel-Klemmkraft je Aktor   */
+#define APPLY_TARGET_FORCE_N   12000U  /* Target clamping force per actuator   */
 #define APPLY_TIMEOUT_50MS     30U     /* 30 * 50ms = 1500 ms        */
-#define HOLD_TOLERANCE_N       1200U   /* 10% von Ziel               */
+#define HOLD_TOLERANCE_N       1200U   /* 10% of target               */
 
 EpbStatus apply_ctrl_init(void);
 
 /**
- * @brief Step-Funktion 50 ms.
+ * @brief 50 ms step function.
  *
  * @reqs SWE-001 SWE-002 SWE-003 SWE-004
  */
@@ -38,6 +38,6 @@ void      apply_ctrl_step_50ms(const ApplyInputs* in);
 
 EpbState  apply_ctrl_get_state(void);
 EpbStatus apply_ctrl_last_error(void);
-uint32_t  apply_ctrl_get_step_count(void);  /* Watchdog-Alive-Counter */
+uint32_t  apply_ctrl_get_step_count(void);  /* Watchdog alive counter */
 
 #endif /* APPLY_CONTROLLER_H */