feat: show Heddle 5.4 agent progress

[roackb2]

Summary

• Bump @roackb2/heddle-remote to 5.4.0 and preserve both reasoning.summary and assistant.commentary activity fields.
• Reconcile cumulative progress by run and provider message ID, remove only the matching placeholder, and keep current-run progress visible through the terminal answer.
• Render provider reasoning in a subdued Markdown-aware card while leaving the labels and presentation policy in SlideX.

Boundary

Reasoning and commentary are user-visible, run-scoped progress—not the authoritative deck result or durable conversation transcript. Raw assistant.stream text remains withheld until the server publishes the product-owned terminal result.

Verification

• npm test
• npm run test:agent (16/16)
• npx tsc --noEmit
• changed-file npx eslint ...
• npm run build
• npm run build:scan-secrets