Earn-core: re-attain & hold CRG grade C (per-dir READMEs + CI test-pass evidence)

[hyperpolymath]

Problem

READINESS.adoc: CRG grade D (provisional, targeting C) — demoted 2026-04-18 per CRG v2.0 STRICT audit. The project is below its own governance bar. Three artefacts are required to re-attain C:

1. A READINESS.adoc at repo root — ✅ now exists.
2. Per-directory README.adoc in the core subtrees — largely missing. Verified 2026-05-19: missing in server/lib/burble, server/lib/burble_web, client/web, client/desktop, client/lib, signaling (present only in ffi/zig).
3. CI test-pass evidence for the Elixir server — partially blocked; see Re-arm Elixir test gate: root-cause mix test --no-start full-app-boot failure (burble#35 item 2) #39 (re-arm Elixir test gate) and Post-#33 follow-ups: Hypatia SARIF integration, re-arm Elixir test gate, remove dead autofix reference #35.

Why it matters

Grade D is the project's own statement that it isn't foundationally ready. Re-attaining and holding C (CI-gated, not a one-off) is the minimum credibility bar for "earn the core".

Acceptance criteria

• Per-directory README.adoc added to every core subtree named in docs/governance/CRG-AUDIT-2026-04-18.adoc.
• Elixir test gate green in CI on every PR (depends on / coordinate with Re-arm Elixir test gate: root-cause mix test --no-start full-app-boot failure (burble#35 item 2) #39).
• READINESS.adoc updated to grade C with the audit reference, and a CI check that fails if the three artefacts regress.

References

READINESS.adoc, docs/governance/CRG-AUDIT-2026-04-18.adoc, .github/workflows/elixir-ci.yml, #39, #35. Part of the Earn-the-Core epic.

[hyperpolymath]

Tracked under the Earn-the-Core epic #53.

[hyperpolymath]

Orienting READMEs landed (PR #58): server/, client/, ffi/, tests/, signaling/, scripts/, bolt/, verification/ — CRG audit blocker #4 addressed. Remaining for #50: CI test-pass evidence (coordinate with #39) + READINESS grade-C bump.