feat(operator-chart): add post-install NOTES.txt (#4615)

[syf2211]

Summary

Adds Helm post-install notes to deploy/charts/operator so helm install prints actionable next steps: verify the operator deployment, check logs, apply a minimal MCPServer example, and find documentation.

Motivation

After helm install, users currently receive no post-installation guidance about verifying the operator, creating their first MCPServer, or where to find docs. Most production Helm charts include NOTES.txt for this first-run experience.

Changes

• templates/NOTES.txt — release metadata, kubectl verification commands, embedded fetch MCPServer manifest (aligned with examples/operator/mcp-servers/mcpserver_fetch.yaml), doc links, and optional namespace RBAC guidance
• tests/notes_test.yaml — helm-unittest coverage for release context, kubectl commands, MCPServer example, and key documentation links

Tests

• helm unittest deploy/charts/operator — 14 suites, 61 tests passed (including 3 new NOTES tests)

Notes

• Default cluster-scoped RBAC is unchanged; namespace-scoped installs get an extra note listing operator.rbac.allowedNamespaces.
• composer-2.5 review: APPROVE

Fixes #4615

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.33%. Comparing base (7c574e2) to head (9e0e215).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5656      +/-   ##
==========================================
- Coverage   70.37%   70.33%   -0.05%     
==========================================
  Files         649      649              
  Lines       66170    66170              
==========================================
- Hits        46568    46541      -27     
- Misses      16231    16277      +46     
+ Partials     3371     3352      -19     

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[ChrisJBurns]

Thanks for the PR @syf2211 a single comment

[ChrisJBurns]

Normally I'd be ok with this, but I've seen this commands (and the CR snippets below) become outdated quickly. We should probably remove section 1, 2 and 3. We can keep 4. Learn more though

[syf2211]

Thanks for the review @ChrisJBurns — updated in 9e0e215. Removed sections 1–3 (kubectl verification, logs, and the MCPServer example) and kept the release context plus documentation links. Updated the helm-unittest suite accordingly (60/60 passing).