chore: publish NeMo MBridge skills

[cuichenx]

Onboarding type

• New product onboarding (new components.d/<slug>.yml file)
• Other (catalog change, README fix, infrastructure, etc.)

This replaces the existing megatron-bridge component slug with nemo-mbridge and registers the signed NeMo MBridge skills for automated catalog sync. It follows the flat, explicit skill-entry pattern used by components.d/nemo-automodel.yml without manually adding catalog skill content in this PR.

For new product onboarding — author affirmations

By submitting this PR, I confirm on behalf of my team:

• Skills cleared for open source release per NVIDIA's internal IP review process (six-question check, all answers affirmative)
• License selected: Apache 2.0 / CC-BY 4.0 / Dual (Apache 2.0 + CC-BY 4.0). Specify: Apache-2.0, matching the 20 upstream SKILL.md frontmatter entries
• No new license or new third-party component introduced beyond what the source repo already carries
• Source repo is public and under an NVIDIA-owned GitHub org
• .agents/skills/ or skills/ path used for new entries (or existing path retained for legacy entries per components.d/<slug>.yml)

Maintainer follow-up before review: please confirm the two unchecked internal/IP-review affirmations above.

Reviewer checklist (OSS Skills PIC)

• Author confirmations above are checked
• components.d/<slug>.yml entry valid (required fields, unique catalog_dir, path exists in source repo, filename slug matches name)
• SKILL.md frontmatter spec-compliant (at least one sampled)
• No new license or third-party dependency requiring OSRB filing

All PRs

• All commits signed off with DCO (git commit -s).
  If you forgot, run git rebase --signoff origin/main && git push --force-with-lease to retroactively sign all commits in your branch.

Other context (for non-onboarding PRs)

Changes:

• Rename component slug file from components.d/megatron-bridge.yml to components.d/nemo-mbridge.yml.
• Change display name to NeMo MBridge.
• Follow the NeMo AutoModel pattern: one explicit customer-facing skill path per skills: entry and flat catalog_dir values.
• Register all 20 signed skills/nemo-mbridge-* directories from NVIDIA-NeMo/Megatron-Bridge for the automated sync workflow.

This PR intentionally does not add files under skills/ or update README.md; those are generated by the sync workflow after the component entry merges.

Validation run locally:

• Parsed components.d/nemo-mbridge.yml and verified 20 entries.
• Verified every entry uses path: skills/<catalog_dir>/.

[mosheabr]

Approved. All 20 NeMo MBridge skills (nemo-mbridge-*) verified 5/5 in NVIDIA-NeMo/Megatron-Bridge — sig + skill-card + evals + BENCHMARK across the board. Largest single-shot signing push of the catalog so far. Flat layout, lowercase, product-prefixed names, license-specify clean. Will follow up with orphan cleanup of skills/Megatron-Bridge/ in a separate PR (same pattern as DeepStream).