Loki Mode v7.54.0

Tech-debt elimination + provider honesty + regression hardening

• Dead-stub removal (P4-3) (loki-ts/src/runner/autonomous.ts): the Bun
  runner carried logStub/noopCouncil/stubProvider fallbacks for modules that all
  exist and conform. These were unreachable dead code that silently degraded to
  wrong results if ever hit. Replaced with a fail-fast requireModule() (a
  missing load-bearing module now errors loudly at resolution time instead of
  producing a wrong build), while genuine runtime-error fallbacks are preserved.
• Antigravity de-listed (P4-5): "Antigravity CLI" was advertised across docs
  as an upcoming Loki provider but had zero implementation, and was misattributed
  to Anthropic (it is Google's product). Removed from all provider tables/lists
  (README, SKILL, CLAUDE, wiki, docs/INSTALLATION). Honest competitor references
  in docs/COMPARISON.md are retained.
• Bun semantic-findings consumer wired (loki-ts/src/runner/build_prompt.ts):
  the Bun semantic-test gate persisted .loki/quality/semantic-findings.txt but
  nothing on the Bun route read it (a writer-with-no-reader). build_prompt.ts now
  reads and injects those severity-tagged findings into the next-iteration prompt,
  independent of gate-failures.txt, byte-parity with the bash route. Absent/empty
  injects nothing.
• Policy-context quoting fix (autonomy/run.sh check_policy): ${2:-{}}
  brace-eating expansion turned a non-empty JSON context into invalid JSON
  ({"a":1}}), so the policy engine received garbage and returned DENY every
  iteration when a .loki/policies.json/.yaml existed (and made the P3-3
  approval-wait unreachable on the live path). Fixed to a split default yielding
  valid {}; non-empty contexts now pass through unchanged. Users with no policy
  file are unaffected.
• Compliance snapshot scheduler (P3-11, optional) (src/audit/compliance-scheduler.js):
  a default-disabled helper that periodically persists a compliance snapshot from
  the real audit chain (honest empty-state, never a fabricated verdict). Ships as
  a tested helper; not yet auto-invoked (documented).
• Regression hardening: added guards for the v7.51-v7.54 features, notably
  tests/test-no-deprecated-codex-flag.sh (fails if any live codex exec --full-auto is reintroduced), plus coverage-artifact, evidence-gate-consumer,
  approval-phase-gate, and semantic-gate-bash-route regression tests.

Gates: local-ci 83/83, full pytest + bun test (1009 Bun tests) + bash/Bun parity
green, 3-reviewer council unanimous APPROVE (after a round that correctly caught a
self-contradicting code comment, now fixed).