docs: reconcile inconsistent test-count and coverage claims (93% gate)

[JohnnyWilson16]

Problem

The stated test/coverage numbers disagree across docs:

• docs/index.md — "1,200+ tests, 93% coverage gate"
• docs/feature-overview.md — "800+ tests, 95%+ coverage"
• Enforced gate in pyproject.toml — --cov-fail-under=93

The 95% / 800+ figures are stale and contradict the enforced 93% gate.

Expected outcome

One consistent, accurate statement everywhere: the coverage gate is 93%, and the test-count claim either matches the real suite or is phrased as a floor ("1,200+").

Relevant files

• docs/index.md
• docs/feature-overview.md
• README.md (double-check its figure too)

Acceptance criteria

• A grep across docs/ and README.md shows a single coverage figure (93%) and no contradictory test-count claims.
• mkdocs build --strict passes.

Difficulty / skills

good first issue — careful reading, Markdown. No code changes.