docs: apply boosts and tag a few things (#4455)

Manual pass to apply a few heuristics:

* Boost conceptual pages
* Deboost (is that a word?) index pages that list all content
* Prefer Agents pages if search query contains the word "agent"
* Add tags for a few selected pages

docs/docs/concepts/durable_execution.md

@@ -1,3 +1,8 @@
+---
+search:
+  boost: 2
+---
+
 # Durable Execution
 
 **Durable execution** is a technique in which a process or workflow saves its progress at key points, allowing it to pause and later resume exactly where it left off. This is particularly useful in scenarios that require [human-in-the-loop](./human_in_the_loop.md), where users can inspect, validate, or modify the process before continuing, and in long-running tasks that might encounter interruptions or errors (e.g., calls to an LLM timing out). By preserving completed work, durable execution enables a process to resume without reprocessing previous steps -- even after a significant delay (e.g., a week later).