Proposal: strengthen Oikoscope repository evidence and submission readiness

## Context
This issue proposes repository improvements to make Oikoscope contributions and outputs easier to verify for external reviewers and collaborators.

## Proposed changes
- Align canonical Oikoscope links across docs and metadata
- Add and clarify verifiable outputs in README/docs (schema, dataset, meeting records)
- Add and verify data validation workflow for `oikoscope/**` changes
- Standardize logo and favicon asset placement for consistent project identity

## Why this matters
These updates improve transparency, reproducibility, and reviewer confidence while keeping process aligned with CHAOSS contribution and governance norms.

## Scope
In scope:
- Documentation, metadata, CI validation, and project assets

Out of scope:
- Non-repository application fields (letters, hourly rate, external endorsements)

## Success criteria
- Public links resolve and are consistent
- Validation runs automatically on relevant changes
- README/docs clearly show current deliverables and evidence