fix(homecore-automation): start engine + implement time/run-mode/choose/template (ADR-161 A3-A7)

A3 (HIGH): homecore-server constructed AutomationEngine then dropped it
immediately while the doc claimed automation was active. Now .start()s the
engine into a long-lived binding (event loop + timer task).

A4 (HIGH): Trigger::Time was hard-coded false with no timer. Added a 1 Hz
wall-clock timer task that fires time: automations when local HH:MM:SS matches
'at' (HH:MM or HH:MM:SS); matches_sync(Time)=false is now correct + documented.

A5 (HIGH): RunMode was documented as AtomicBool-enforced but every trigger
spawned unbounded parallel. Each automation now carries a running AtomicBool;
Single/IgnoreFirst skip re-entrant triggers, Parallel fires every time.
(Bounded Queued/Restart/max → ACCEPTED-FUTURE, honestly stated in the doc.)

A6 (HIGH): Action::Choose discarded choices and always ran default. Now
deserialises each branch's conditions, evaluates them, and runs the first
matching branch; default only if none match.

A7 (MEDIUM): template: conditions were always false in the engine path
(EvalContext built with template_env: None). The engine now builds a
TemplateEnvironment over the state machine and threads it into every
EvalContext (event loop, timer, Choose).

Tests (fail on old source):
- engine_behaviors::time_trigger_fires_via_timer_path (A4)
- engine_behaviors::single_mode_does_not_double_fire_on_rapid_triggers (A5; old fired 2x)
- engine_behaviors::parallel_mode_does_fire_concurrently (A5)
- action::choose_runs_matching_branch_not_default (A6; old ran default)
- engine_behaviors::template_condition_evaluates_true_in_engine (A7; old always false)

engine.rs kept <500 lines; behavioral tests moved to tests/engine_behaviors.rs.

Co-Authored-By: claude-flow <ruv@ruv.net>

v2/crates/homecore-automation/src/trigger.rs

@@ -150,7 +150,12 @@ impl Trigger {
                 true
             }
             Trigger::Time { .. } => {
-                // Time triggers are evaluated by the engine's timer task, not here.
+                // Time triggers are wall-clock based and have no state-change
+                // context to match here. They are evaluated by the engine's
+                // 1 Hz timer task (`AutomationEngine::start_timer`, HC-WS-04 /
+                // ADR-161), which compares the trigger's `at` against the local
+                // wall-clock second. `matches_sync` therefore returns false for
+                // `Time` on the state-change path by design.
                 false
             }
             Trigger::Event { event_type } => {