Reconcile starter documentation with files that actually ship

[koniz-dev]

Context

Several committed guides present non-existent starter files as usable APIs: hooks/README.md and docs/color-themes.md reference hooks/useThemeColor.ts; components/README.md references ThemedText.tsx and ThemedView.tsx; and scripts/README.md documents scripts/reset-project.js, which is not committed. This makes a fresh starter checkout misleading.

Acceptance criteria

1. Every documented local file import or script command in README files and docs/ resolves to a committed file, or is explicitly marked as an optional create-it-yourself example with complete creation steps.
2. The docs accurately describe the shipped Paper theme and loading/error components.
3. A repository check (automated where practical) verifies local Markdown links and code-path references in the corrected scope.
4. npm run format:check passes.

[koniz-dev]

PASS — documentation references now resolve to shipped helpers and the nonexistent reset command is explicitly documented as unavailable. Evidence: . Commit: 0cc8d39 plus this documentation commit.

[koniz-dev]

PASS correction: evidence is docs/evidence/issue-12/verification.md. Commit e9fc610 adds the shipped helper APIs and corrected documentation; lint, type-check, Jest (6 suites / 40 tests), and format passed.