Use meta.stats from spec payload in BadgeTable template

[a6b8]

Context

Per Memo 059 Phase 4 PRD-018, the dot-github profile generator must source schema stats (count_schemas, count_unique_datasources, count_tools, count_resources, count_skills) from the flowmcp-spec payload's meta.stats block — NOT directly from flowmcp-schemas-public. This keeps the spec payload as the Single-Source-of-Truth for downstream consumers.

Scope

• Extend scripts/fetch-refs.mjs to also fetch generated/docs-payload/manifest.json from flowmcp-spec and merge meta.stats into refs.json under a stats key
• Extend src/lib/placeholder-replace.mjs regex to recognize {{stats.*}} placeholders
• Null fallback: render — instead of crashing when stats value is null (handles spec-payload null block)
• Update src/data/template.txt: replace hardcoded "530+ curated API schemas" with dynamic {{stats.count_schemas}} etc.
• Build fail-safe: manifest fetch failures fall back to null block, BadgeTable still renders

Acceptance

• No direct fetch from flowmcp-schemas-public (verified via grep — only badge-config references remain)
• npm run fetch-refs && npm start succeeds with null stats (current state: upstream manifest pre-PRD-016)
• Happy path tested locally with injected stats (365 schemas, 288 datasources, 1575 tools)
• Build never crashes on null stats

Reference

• Memo 059 REV-04 chapter 7 (Stats-Pipeline)
• PRD-018_stats-dotgithub-read.md
• Depends on Embed stats.json in spec manifest meta.stats with fallback flowmcp-spec#45 (meta.stats embedding)