chore(plugin): update service recommendation

[krokoko]

Summary

• AWS App Runner has entered maintenance mode — the plugin must not recommend it for new workloads.
• Replaced every App Runner reference in the deploy-on-aws plugin with ECS Express Mode.
• Added an explicit maintenance-mode warning in defaults.md and a hard principle in SKILL.md so the agent never falls back to App Runner based on general training data.

Changes

File	What changed
skills/deploy/references/defaults.md	Add a ⚠️ App Runner maintenance-mode warning block
skills/deploy/SKILL.md	Added principle: "Never recommend AWS App Runner — use ECS Express mode instead"
skills/aws-architecture-diagram/references/example-complex-platform.drawio	Swapped mxgraph.aws4.app_runner icon and label → mxgraph.aws4.ecs / "ECS Fargate"; updated legend text
skills/aws-architecture-diagram/references/aws4-shapes-services.md	Annotated app_runner shape as (maintenance mode — use ecs/fargate instead)

Build & test results

mise run build  →  PASS
  lint:md           ✅  0 errors
  lint:manifests    ✅  all JSON schemas valid
  lint:cross-refs   ✅  0 errors / 0 warnings
  fmt:check         ✅  no formatting issues
  validate:refs     ✅  146/153 reachable (7 pre-existing orphans, unchanged)
  validate:size     ✅  22 skills, 0 over limit
  security:bandit   ✅  no issues
  security:semgrep  ✅  no issues
  security:gitleaks ✅  no leaks
  security:checkov  ✅  71 passed, 0 failed
  security:grype    ✅  no vulnerabilities

Decisions made

• fix_icon_colors.py and aws4-shapes.json left unchanged — app_runner is still a valid AWS4 draw.io shape and may appear in existing customer diagrams. The python script and shape registry are purely declarative; leaving them avoids breaking any diagram that happens to already use the shape. The aws4-shapes-services.md annotation is sufficient to steer the agent away from generating new App Runner nodes.
• ecs icon used in the diagram (not fargate) — the ECS service-level icon is in the Compute category with the same orange palette, making it a visually consistent drop-in replacement while also conveying the orchestration layer.

Agent notes

What went well:

• App Runner references were well-isolated: one example diagram, one shape reference file, and the two skill instruction files. No logic code needed changing.
• The mise run build pipeline is comprehensive and fast — a single command validates markdown, schemas, cross-refs, formatting, and security in one shot.

Difficulties:

• aws4-shapes-services.md is a single long line per category, so the "maintenance mode" annotation had to be inserted inline rather than on a new line.
• "ECS Express mode" is not a named AWS product; interpreted as "ECS Fargate in a simple / express configuration" — the most natural App Runner replacement.

Patterns discovered:

• CLAUDE.md / AGENTS.md are symlinked — always edit AGENTS.md.
• Orphaned .drawio files in references/ are expected and pre-existing (7 files); validate:refs reports them as warnings, not errors.
• Commit messages follow conventional-commit format type(scope): description.

Suggestions for future tasks:

• Consider adding an explicit "deprecated services" section to defaults.md as AWS services transition to maintenance mode (App Runner won't be the last).
• The fix_icon_colors.py shape-colour map could be auto-generated from aws4-shapes.json to reduce duplication.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of the project license.

[scoropeza]

LGTM