docs: add future integrations assessment directory (#1037)

Creates a structured directory for documenting and evaluating potential
data source integrations that are considered but deferred or not
currently implemented.

Includes initial OpenAPC assessment which concludes:
- Limited coverage (5-15% of queries)
- Weak signal for predatory detection (cost ≠ quality)
- Defer integration unless scope expands to cost transparency

This provides a permanent record of integration evaluations to inform
future decisions and avoid re-analyzing the same data sources.

Co-authored-by: florath-ai-assistant[bot] <Andreas.Florath@telekom.de>

Author: coding-ai-assistant[bot]

docs/future-integrations/README.md

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+# Future Integrations and Data Sources
+
+This directory contains assessments and evaluations of potential data sources and integrations that have been considered for aletheia-probe but are currently deferred or not implemented.
+
+## Purpose
+
+Each file in this directory documents:
+- **What** the data source or integration is
+- **Why** it was considered
+- **Pros and cons** of integration
+- **Technical feasibility** and effort estimates
+- **Recommendation** (defer, low priority, or conditions for implementation)
+
+## Current Assessments
+
+- **[openapc.md](openapc.md)** - OpenAPC (Article Processing Charges) integration assessment
+  - **Status**: Deferred / Low Priority
+  - **Reason**: Limited coverage (5-15% of queries), weak signal for predatory detection, cost data ≠ quality indicator
+  - **Reconsider if**: Scope expands to include cost transparency, user demand, or for research use cases
+
+## Adding New Assessments
+
+When evaluating a new potential integration:
+
+1. Create a new markdown file named after the data source (e.g., `scopus-alternative.md`, `pubpeer.md`)
+2. Use the OpenAPC assessment as a template structure
+3. Include at minimum:
+   - Context and overview of the data source
+   - Pros and cons analysis
+   - Integration effort estimate
+   - Coverage and benefit analysis
+   - Alignment with aletheia-probe's mission
+   - Clear recommendation with reasoning
+   - Sources and references
+
+## Philosophy
+
+Not every available data source should be integrated. Consider:
+
+- **Mission alignment**: Does it directly support predatory journal detection?
+- **Coverage**: What percentage of queries benefit?
+- **Signal strength**: Is it direct evidence or weak/ambiguous signal?
+- **Maintenance burden**: Is the effort justified by the benefit?
+- **Alternatives**: Could existing backends be improved instead?
+
+Focus should remain on **high-impact integrations** that meaningfully improve detection accuracy for the majority of queries.