spec(hello-world): GitHub Pages hosting for product page and product demo

[Luis85]

Summary

Adds specs/hello-world/github-pages.md (SPEC-HW-001), updated to align with the ratified event taxonomy, CI gate philosophy, and SAO orchestrator integration.

What changed from the original

Area	Original issue	Fixed
Event names	Used assumed names (workflow.started, agent.invoked, agent.completed, workflow.completed) that don't match the runtime's event model	Updated to preliminary names from #15/#21: session.started, agent.spawned, command.dispatched, artifact.created, session.stopped
Event payload	No mention of traceId, seq, eventId	Each event entry must show eventId, traceId, seq, type
CI design (pages.yml)	Flat step list with no gate distinction	Hard gates (file existence, HTML validity, no undisclosed external scripts) vs. soft gate (reachability — retry once, advisory failure) per #29
Error messages	No format specified	Each pages.yml error follows the agent-readable format from #28 (violation + fix instruction + docs link)
Integration map	Missing SAO	docs/index.html must include SAO orchestrator engine in the integration map
Living-spec notice	Not present — demo was implicitly fictional	Explicit notice: event names and demo content must be verified against actual examples/hello-world/index.ts output before merge; cross-references to #14, #15, #21 as authoritative sources

Key design principle added

The demo page (docs/demo.html) is a rendered snapshot of a real run, not a fictional example. Event names must match the ratified RuntimeEvent union from #15 §7. This spec will need one final pass after #15 closes to confirm the event table.

Test plan

• Review spec content against issue Milestone: Hello World — first end-to-end runtime proof (v0.1.0) #8 and PRD §11 (UX Entry Points)
• Event table uses preliminary names from Phase 1 · Data model — runtime entities, definitions, events, and projections #15/Phase 1 · Failure-event taxonomy — which *.failed events ship in V1 #21 with explicit note to verify against actual run output
• docs/index.html requirements include SAO in the integration map
• pages.yml has hard/soft gate split per Phase 2 · CI workflow — typecheck, test, surface review, build #29 (existence + HTML validity = hard; reachability = soft with retry)
• Each pages.yml error message follows agent-readable format per Phase 2 · Engineering scaffold: lint, format, commit conventions #28
• Living-spec notice is present and references Phase 1 · Architecture proposal v1 — runtime kernel, event bus, and module layout #14, Phase 1 · Data model — runtime entities, definitions, events, and projections #15, Phase 1 · Failure-event taxonomy — which *.failed events ship in V1 #21 as authoritative sources
• Terminology consistent with PRD and docs/product-page.md

Relates to #8

https://claude.ai/code/session_017U6JmCXpzcspdtzvck4SsL