simplify: drop decorative dash-rule lines from section banners

[devin-ai-integration]

Summary

• Deletes the two dash-only rule lines (// ----…) from every three-line decorative section banner, keeping each label as a plain // comment.
• 103 banners across 37 production files; 207 comment lines removed, zero code touched.

Motivation

Cleanup-scan finding sfind-4b20dbfacfa4445d84f8b1ad4ddca804: the repo-wide // ---- / label / // ---- banner style is pure decoration — the single label line already names each section, and AGENTS.md directs comments to explain invariants rather than narrate. This one sweep covers the reported sites (dart_extractor and siblings in tracedecay-agent-hosts, tracedecay-code-extraction, tracedecay-mcp, tracedecay-query, tracedecay-runtime-core, tracedecay-project, dashboard) plus unscanned sites with the identical banner in tracedecay-automation-runtime, tracedecay-global-db, tracedecay-sessions, tracedecay, plugin/pi, and mockups.

Changes

• crates/: 31 files, banner rule lines removed only (e.g. dart_extractor.rs −32 lines).
• dashboard/: evidence.ts, codegen/generate.ts, EvidenceSummaries.tsx; the "Plan 26" label was reworded to // Dimension bands (adoption, retrieval, budgets) per the no-plan-names convention.
• plugin/pi/index.ts, mockups/ui-concept-v2/…/BrainCanvas.tsx: same banner shape.
• Preserved: the explanatory paragraph under the Shared MCP server registration label in host_config_io.rs (and the equivalent paragraph in project_registry.rs), and multi-line labels such as the resolver note in generate.ts. Test files untouched.

Test plan

• cargo check on all 10 touched crates passes
• cargo fmt --all -- --check passes
• pnpm run typecheck (dashboard) passes
• cargo nextest run --workspace --no-fail-fast (not run — comment-only deletions, no behavior surface)

Checklist

• CHANGELOG.md not needed (comment-only cleanup, no release-note surface)
• No secrets, credentials, or .env files included
• Breaking changes documented (none)

Link to Devin session: https://app.devin.ai/sessions/674a37eb35ff442aaa725f34dbf18513
Open in Devin Desktop: https://app.devin.ai/desktop/session/674a37eb35ff442aaa725f34dbf18513?variant=devin
Requested by: @ScriptedAlchemy

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[devin-ai-integration]

I'll fix CI failures and address comments from users with write access. I'll skip comments containing "(aside)".

• Disable automatic comment, CI, and merge conflict monitoring

[changeset-bot]

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Latest commit: a9bb475

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[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.