feat(mcp): add live analytics tools backed by shared loaders

[bohdansolovie]

Summary

• Adds src/analytics-live.mjs with shared live analytics loaders (loadSubnetUptime, loadRegistryLeaderboards, loadCompareSubnets, loadGlobalIncidents) for MCP tools.
• Adds four MCP tools mirroring REST analytics endpoints:
  • get_subnet_uptime → /api/v1/subnets/{netuid}/uptime
  • get_registry_leaderboards → /api/v1/registry/leaderboards
  • compare_subnets → /api/v1/compare
  • get_global_incidents → /api/v1/incidents
• Reuses composeCompareData from workers/request-handlers/analytics-routes.mjs (refactor(api): extract deferred analytics routes from api.mjs #1919) — no api.mjs handler reversion, no logic duplication.

Closes #1958

Resubmission of #1960: single commit by bohdansolovie, rebased on latest main after #1919 landed.

Test plan

• npm test -- tests/analytics-live.test.mjs tests/compare.test.mjs tests/mcp-server.test.mjs
• npm run lint
• npm run build (derived artifacts fresh)

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[codecov]

Codecov Report

❌ Patch coverage is 84.25197% with 20 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.12%. Comparing base (796da14) to head (9529df4).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/analytics-live.mjs	87.23%	1 Missing and 11 partials ⚠️
src/mcp-server.mjs	75.75%	0 Missing and 8 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2046      +/-   ##
==========================================
- Coverage   93.26%   93.12%   -0.15%     
==========================================
  Files          48       49       +1     
  Lines        7755     7878     +123     
  Branches     2839     2899      +60     
==========================================
+ Hits         7233     7336     +103     
- Misses         92       94       +2     
- Partials      430      448      +18     

Files with missing lines	Coverage Δ
src/mcp-server.mjs	87.80% <75.75%> (-0.71%)	⬇️
src/analytics-live.mjs	87.23% <87.23%> (ø)

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[JSONbored]

Closes #1958 (open, wanted). Four new MCP tools (get_subnet_uptime, get_registry_leaderboards, compare_subnets, get_global_incidents) backed by src/analytics-live.mjs. The new loaders are correct extractions of the REST-layer logic; the MCP tool definitions in src/mcp-server.mjs are well-formed. Substantively good.

Same block as #2032: the diff includes public/.well-known/mcp/server-card.json (committed under the old workflow) and also public/metagraph/operational-surfaces.json + public/metagraph/r2-manifest.json (generated build artifacts that should never be committed). #2055 deleted the server-card from git, causing a conflict. Closing. Resubmit with three files dropped from the diff entirely: public/.well-known/mcp/server-card.json, public/metagraph/operational-surfaces.json, public/metagraph/r2-manifest.json. The analytics-live module and the MCP tool additions are clean — I'll take them on a fresh branch.