[instructions] Sync instruction files with release v0.84.0

[github-actions]

Summary

Routine Instructions Janitor pass. Latest GitHub-marked release is v0.83.4 (2026-07-27); v0.84.0 is a newer pre-release (2026-07-29). Comparing v0.83.4...main found no docs/ changes but 10 already-synced .github/aw/ changes (pagination guidance, engine copilot-sdk split, trigger escalation rules, etc.) plus actions-lock.json pin churn - no action needed there. The Size audit found 3 files over the 400-line limit, which is what this PR fixes, plus 2 accuracy gaps found via schema/code review.

Files changed (before -> after line counts):

• github-mcp-server.md: 431 -> 382 (pagination section extracted)
• syntax-agentic.md: 440 -> 361 (engine: field extracted)
• token-optimization.md: 422 -> 374 (Techniques 9-11 extracted)
• triggers.md: trimmed internal duplication (escalation rules vs no-op expectations restated the same rule twice) and cross-linked to the incident dedup-key templates in create-agentic-workflow-trigger-details.md
• safe-outputs-runtime.md: documented safe-outputs.data (structured-data schema for body-based safe outputs) - present in pkg/parser/schemas/main_workflow_schema.json and pkg/workflow/safe_outputs_data_schema.go but undocumented
• syntax-engine.md (new): documented engine.auth.provider: gcp (Vertex AI WIF fields) alongside existing azure/anthropic providers
• New split files: github-mcp-server-pagination.md, syntax-engine.md, token-optimization-caching-budgets.md - each cross-linked from its parent file and from the relevant index (github-agentic-workflows.md reference table, syntax.md schema index)

Documentation commits reviewed: none (docs/ unchanged since v0.83.4) - reviewed the .github/aw/ diff directly (10 files) via gh api repos/github/gh-aw/compare/v0.83.4...main, since this sandbox has a shallow git clone with no local tag history.

Duplication removed: internal restatement in triggers.md's workflow_run failure-triage section (escalation rules and no-op expectations covered the same open-incident-suppression rule twice); confirmed no other significant cross-file duplication in the persona-matrix, recompilation-rule, or single-job-constraint patterns (all already use short cross-references, not restatement).

Size confirmation: all .github/aw/*.md files are now under their target limits.

Test plan

• wc -l .github/aw/*.md confirms no file exceeds 400 lines
• Verified no other file references the moved sections by stale anchor
• Cross-checked engine.auth and safe-outputs.data schema definitions in pkg/parser/schemas/main_workflow_schema.json and pkg/workflow/safe_outputs_data_schema.go against the new instruction text

Generated by 🧹 Instructions Janitor · sonnet50 · 418.9 AIC · ⌖ 13.8 AIC · ⊞ 5.6K · ◷

• expires on Aug 1, 2026, 1:38 AM UTC-08:00

[github-actions]

🎉 This pull request is included in a new release.

Release: v0.84.1