Consolidate documentation: move maintainer docs to docs/, remove redundant files

- Move RELEASING.md and LINTING.md to docs/ (maintainer-only content)
- Delete WORKFLOW.md (agent workflow content belongs in AGENTS.md)
- Delete TEXT_FORMATS.md (technical details belong in ADVANCED.md)
- Update all cross-references to point to new locations
- Keep CLAUDE.md (required by Claude Code)

Reduces root-level docs from 20 to 16 files with clearer organization.

Amp-Thread-ID: https://ampcode.com/threads/T-fe1db4f3-16c6-4a79-8887-c7f4c1f11c43
Co-authored-by: Amp <amp@ampcode.com>

README.md

@@ -444,7 +444,7 @@ For advanced usage, see:
 - **[ADVANCED.md](ADVANCED.md)** - Prefix renaming, merging duplicates, daemon configuration
 - **[CONFIG.md](CONFIG.md)** - Configuration system for integrations
 - **[EXTENDING.md](EXTENDING.md)** - Database extension patterns
-- **[TEXT_FORMATS.md](TEXT_FORMATS.md)** - JSONL format and merge strategies
+- **[ADVANCED.md](ADVANCED.md)** - JSONL format and merge strategies
 
 ## Documentation
 
@@ -457,7 +457,7 @@ For advanced usage, see:
 - **[LABELS.md](LABELS.md)** - Complete label system guide
 - **[CONFIG.md](CONFIG.md)** - Configuration system
 - **[EXTENDING.md](EXTENDING.md)** - Database extension patterns
-- **[TEXT_FORMATS.md](TEXT_FORMATS.md)** - JSONL format analysis
+- **[ADVANCED.md](ADVANCED.md)** - JSONL format analysis
 - **[PLUGIN.md](PLUGIN.md)** - Claude Code plugin documentation
 - **[CONTRIBUTING.md](CONTRIBUTING.md)** - Contribution guidelines
 - **[SECURITY.md](SECURITY.md)** - Security policy