feat: cache warmer in memory switchover

[SkArchon]

Adds docs for the in memory switchover fallback, depends on PR wundergraph/cosmo#2445

Summary by CodeRabbit

• Documentation
  • Expanded cache warming documentation with comprehensive coverage of CDN-based and in-memory fallback caching strategies, including configuration options and performance trade-offs.
  • Updated configuration reference with new cache warming options and restructured source configuration for CDN and filesystem paths.
  • Enhanced deployment guidance addressing latency implications with cache warming mitigation strategies.

[StarpTech]

LGTM

[coderabbitai]

Caution

Review failed

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Walkthrough

Documentation updates introduce cache warming strategies across multiple files. The cache-warmer concept file restructures content to distinguish CDN-based warming from in-memory fallback approaches. Configuration documentation adopts explicit naming conventions and a nested source structure. Deployment documentation references the new cache warming capability.

Changes

Cohort / File(s)	Summary
CDN and In-Memory Cache Warming Concepts docs/concepts/cache-warmer.mdx	Restructures content with new section headers distinguishing CDN-based cache warming from in-memory fallback approaches. Adds comprehensive details on how each strategy works, configuration guidance, key characteristics, and operational tradeoffs.
Cache Warmer Configuration docs/router/configuration.mdx	Updates environment variable naming to CACHE_WARMUP_* convention. Introduces CACHE_WARMUP_IN_MEMORY_FALLBACK option. Restructures source configuration from simple path to nested structure with filesystem.path and cdn.enabled fields. Updates YAML examples accordingly.
Deployment Documentation docs/router/deployment/config-hot-reload.mdx	Updates section heading to include cache warming context. Removes specific note about warming top 100 operations and replaces with reference to cache warming mitigation capability and documentation link.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'feat: cache warmer in memory switchover' directly describes the main feature being documented - the in-memory fallback cache warming capability, which aligns with the primary changes across all three documentation files.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@docs/concepts/cache-warmer.mdx`:
- Line 9: Update the heading "How CDN Based Cache Warming Works" to hyphenate
the compound adjective: change "CDN Based" to "CDN-Based" in the
docs/concepts/cache-warmer.mdx heading (the string "How CDN Based Cache Warming
Works") so it reads "How CDN-Based Cache Warming Works".