Loki Mode v7.51.0

Tech-debt closure: four inert/half-wired features made real (both routes)

This release removes scaffolding that read like a feature but did nothing,
honoring the no-tech-debt mandate. Each activation is advisory-first and
deny-filters clean results, so an activated gate can never false-fire and
deadlock the autonomous loop. Defaults are unchanged for existing users.

• Coverage artifact honesty (autonomy/run.sh): at the default (measurement
  off) the coverage block was skipped entirely, so no coverage.json was ever
  written -- a missing-artifact gap in the reproducibility manifest. The gate now
  writes coverage.json with measured:false even when measurement is off, with
  zero added runtime (no instrumented re-run) and no blocking. Measurement stays
  opt-in (LOKI_COVERAGE_GATE=1); default-on would double every test run.
• LSP-diagnostics gate made real on both routes: the gate read
  .loki/quality/lsp-diagnostics.json but nothing wrote it (inert). A
  route-neutral writer (mcp/lsp_proxy.py --write-diagnostics) is now invoked
  identically from the Bun gate (loki-ts/src/runner/quality_gates.ts) and the
  bash gate (autonomy/run.sh), with byte-identical blocking semantics: single
  knob LOKI_GATE_LSP_DIAGNOSTICS (default off); count_errors > 0 blocks only
  when enabled; absent/malformed/clean never fires; no language server present ->
  writes nothing (never fabricates a clean verdict). LOKI_GATE_LSP_WRITER=0
  lets a caller supply a pre-built artifact. The bash/Bun parity test now
  validates these as genuinely shared toggles (prior bun-only carve-out removed).
• Evidence-gate-details consumer (autonomy/run.sh, closes P1-1): the
  completion council wrote .loki/council/evidence-gate-details.json but run.sh
  had no consumer. run.sh now surfaces the details advisory (WARN on block, INFO
  otherwise) without introducing a new block; the wrapper preserves the gate's
  exact return code, so completion detection is unchanged. Absent/malformed file
  degrades silently.
• Approval phase-gate enforcement (autonomy/run.sh): a policy
  "approval required" result (exit 2) previously logged and proceeded. It now
  honors an approval wait on .loki/signals/POLICY_APPROVED|POLICY_REJECTED
  (same mechanism as staged autonomy) when LOKI_STAGED_AUTONOMY=true or
  LOKI_POLICY_APPROVAL_ENFORCE=1. With neither knob set, behavior is unchanged
  (advisory log + proceed).

Gates: local-ci 78/78, full pytest + bun test + bash/Bun parity matrix green,
3-reviewer council unanimous APPROVE (2 Opus adversarial + 1 Sonnet).