fix(rebrand): full-cutover rename Prometheus/Alertmanager/Grafana observability identifiers

[JSONbored]

Summary

• Rebrand epic Epic: complete the gittensory -> loopover rebrand (full cutover, no dual-support) #5705, Phase 8a follow-up: renames the last unrenamed identifier surface in the observability stack.
• Prometheus scrape job (job_name: gittensory → loopover, gittensory-backup → loopover-backup, matching the already-renamed loopover:8787 compose service) and the up{job="gittensory"} == 0 expr the LoopoverTargetDown alert reads it through.
• The three AMS-miner alert rule group names (gittensory-miner-prediction/-portfolio-queue/-governor → loopover-miner-*) — confirmed no Alertmanager routing config depends on these group names before renaming.
• Directly-adjacent stale prose discovered while verifying: runbook/summary text quoting the already-renamed loopover-miner CLI, alertmanager.yml's header comment + docs URL (updated to the canonical loopover.ai domain), and Grafana dashboard description strings in ai-usage.json/miner-usage.json/resource-hub.json/ams-ledgers.yml.

Deliberately not touched: the real JSONbored/gittensory GitHub repo and Sentry-project references embedded in these same dashboard files.

Test plan

• npm run typecheck clean
• npx vitest run — 838 files / 16257 tests passed (2 pre-existing skips)
• npm run selfhost:validate-observability clean
• full npm run test:ci gate green end-to-end

[superagent-security]

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

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.07%. Comparing base (e85528a) to head (5da3959).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5768   +/-   ##
=======================================
  Coverage   95.07%   95.07%           
=======================================
  Files         582      582           
  Lines       46212    46212           
  Branches    14819    14819           
=======================================
  Hits        43936    43936           
  Misses       1516     1516           
  Partials      760      760           

Flag	Coverage Δ
shard-1	43.40% <ø> (-0.54%)	⬇️
shard-2	36.01% <ø> (+0.25%)	⬆️
shard-3	32.20% <ø> (-0.06%)	⬇️
shard-4	32.80% <ø> (-0.12%)	⬇️
shard-5	31.34% <ø> (-0.40%)	⬇️
shard-6	44.99% <ø> (+0.34%)	⬆️

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