spec(MCP): Add specification for RedisVL MCP server (only for review; do not merge)

[vishal-bala]

Recreating this PR to separate the spec branch from the development branches. Development will be merged gradually into this epic branch, so that we can PR a functional MCP server into main when it's ready.

This PR (not to be merged) introduces a specification document for the RedisVL MCP framework. The goal is to have a clear design document to guide agentic development on this feature.

---

Note

Low Risk
Primarily adds documentation; the only code-adjacent change is a uv.lock version bump for the editable redisvl package, which could affect reproducibility but not runtime behavior.

Overview
Adds a new spec/MCP.md design/specification document defining the planned RedisVL MCP server contract (config schema, lifecycle, tool APIs for redisvl-search/redisvl-upsert, error codes, and test plan).

Also updates uv.lock to reflect a redisvl version bump to 0.15.0 for the editable package entry.

^{Written by Cursor Bugbot for commit 2f58b0f. This will update automatically on new commits. Configure here.}

[jit-ci]

🛡️ Jit Security Scan Results

✅ No security findings were detected in this PR

---

^{Security scan by Jit}