[Search] Cleanup Search TOC, move/rename files

[leemthompo]

https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/388/solutions/search.html

TODO

• synonyms

SUMMARY

The structure is now cleaner with content grouped more logically and less deeply nested.

1. Moved "Build your search queries" (formerly "Query languages for search") content under clear hierarchy and renamed it to be more action-oriented

2. Consolidated relevance-related content under full-text search:

full-text.md
└── search-relevance.md
    ├── mixing-exact-search-with-stemming.md
    ├── consistent-scoring.md
    └── static-scoring-signals.md

3. Consolidated all inference-related content under ai-search:

ai-search
└── inference-api
    └── [various integrations].md

4. Consolidated search query-related APIs:

querying-for-search.md
├── the-search-api.md
├── async-search-api.md
├── retrievers-overview.md
└── search-templates.md

5. Removed the separate "examples" folder and integrated those files where they logically belong

6. Moved most query-related topics under "Build your search queries" for better organization

7. Structure:

• Templates under queries rather than top-level
• Search apps consolidated into single path
• Behavioral analytics under site-or-app

8. Navigation:

• Added navigation_title metadata
• Fixed mapped URLs

9. Mapping:

• Added proper mapped_urls metadata
• Cleaned up redundant mappings

10. Code/API organization:

• Search API examples in reference sections
• API content under clear hierarchy