Improve Heartbeat filter (#5451)

* optimistic mode

* fix space

* Fix line length

* Add examples

* Clean up example

---------

Co-authored-by: Jonathan Swoboda <[email protected]>

Author: pkejval

content/components/sensor/filter/heartbeat.md

@@ -3,9 +3,29 @@ description: ""
 headless: true
 ---
 
-Send the value periodically with the specified time interval.
-If the sensor value changes during the interval the interval will not reset.
-The last value of the sensor will be sent.
+Send the sensor value periodically at the specified time interval. If the sensor value changes
+during this interval, the timer will not reset — the last known value of the sensor will still
+be sent when the interval elapses.
 
-So a value of `10s` will cause the filter to output values every 10s regardless
-of the input values.
+For example, a value of `10s` will cause the filter to output the last known value every 10 seconds,
+regardless of how often the input value changes.
+
+When using `optimistic` mode, the filter will still repeat the last known value at the configured interval,
+but in addition, every new incoming value is published immediately as it arrives. This ensures that the
+sensor output updates instantly on change, while maintaining a steady periodic "heartbeat" of the last value
+between updates. This mode is useful for sensors where immediate responsiveness is desired.
+
+Configuration variables:
+
+- **period** (Required, time): The interval at which the last known value is republished.
+- **optimistic** (*Optional*, boolean): When enabled, every new incoming value is published immediately as it
+  arrives, regardless of the configured time interval.
+
+```yaml
+# Example filters
+filters:
+  - heartbeat: 5s
+  - heartbeat:
+      period: 5s
+      optimistic: true
+```