Remove the deprecated Claude subscription login path and restore a green Rust workspace

ROADMAP #37 was still open even though several earlier backlog items were
already closed. This change removes the local login/logout surface, stops
startup auth resolution from treating saved OAuth credentials as a supported
path, and updates diagnostics/help to point users at ANTHROPIC_API_KEY or
ANTHROPIC_AUTH_TOKEN only.

While proving the change with the user-requested workspace gates, clippy
surfaced additional pre-existing warning failures across the Rust workspace.
Those were cleaned up in-place so the required `cargo fmt`, `cargo clippy
--workspace --all-targets -- -D warnings`, and `cargo test --workspace`
sequence now passes end to end.

Constraint: User explicitly required full-workspace fmt/clippy/test before commit/push
Constraint: Existing dirty leader worktree had to be stashed before attempted OMX team worktree launch
Rejected: Keep login/logout but hide them from help | left unsupported auth flow and saved OAuth fallback intact
Rejected: Stop after ROADMAP #37 targeted tests | did not satisfy required full-workspace verification gate
Confidence: medium
Scope-risk: moderate
Reversibility: clean
Directive: Do not reintroduce saved OAuth as a silent Anthropic startup fallback without an explicit supported auth policy
Tested: cargo fmt --all --check; cargo clippy --workspace --all-targets -- -D warnings; cargo test --workspace
Not-tested: Remote push effects beyond origin/main update

ROADMAP.md

@@ -438,7 +438,7 @@ Model name prefix now wins unconditionally over env-var presence. Regression tes
 
 36. **Custom/project skill invocation disconnected from skill discovery** -- dogfooded 2026-04-09. /skills lists custom skills (e.g. caveman) but bare skill-name invocation does not dispatch them; falls through to plain model prompt. Fix: audit classify_skills_slash_command, ensure any skill listed by /skills has a deterministic invocation path, or document the correct syntax. Source: gaebal-gajae dogfood 2026-04-09.
 
-37. **Claude subscription login path should be removed, not deprecated** -- dogfooded 2026-04-09. Official auth should be API key only (ANTHROPIC_API_KEY or OAuth access token via ANTHROPIC_AUTH_TOKEN). claw login with Claude subscription credentials creates legal/billing ambiguity. Fix: remove the subscription login surface entirely; update README/USAGE.md to say API key is the only supported path. Source: gaebal-gajae policy decision 2026-04-09.
+37. **Claude subscription login path should be removed, not deprecated** -- dogfooded 2026-04-09. Official auth should be API key only (`ANTHROPIC_API_KEY`) or OAuth bearer token via `ANTHROPIC_AUTH_TOKEN`; the local `claw login` / `claw logout` subscription-style flow created legal/billing ambiguity and a misleading saved-OAuth fallback. **Done (verified 2026-04-11):** removed the direct `claw login` / `claw logout` CLI surface, removed `/login` and `/logout` from shared slash-command discovery, changed both CLI and provider startup auth resolution to ignore saved OAuth credentials, and updated auth diagnostics to point only at `ANTHROPIC_API_KEY` / `ANTHROPIC_AUTH_TOKEN`. Verification: targeted `commands`, `api`, and `rusty-claude-cli` tests for removed login/logout guidance and ignored saved OAuth all pass, and `cargo check -p api -p commands -p rusty-claude-cli` passes. Source: gaebal-gajae policy decision 2026-04-09.
 
 38. **Dead-session opacity: bot cannot self-detect compaction vs broken tool surface** -- dogfooded 2026-04-09. Jobdori session spent ~15h declaring itself "dead" in-channel while tools were actually returning correct results within each turn. Root cause: context compaction causes tool outputs to be summarised away between turns, making the bot interpret absence-of-remembered-output as tool failure. This is a distinct failure mode from ROADMAP #31 (executor quirks): the session is alive and tools are functional, but the agent cannot tell the difference between "my last tool call produced no output" (compaction) and "the tool is broken". Downstream: repetitive false-dead signals in the channel, work not getting done despite the execution surface being live. Fix shape: (a) probe with a short known-output command at turn start if context has been compacted; (b) gate "I am dead" declarations behind at least one within-turn tool call with a verified non-empty result; (c) consider adding a session-health canary cron that fires a wake with a minimal probe and checks the result. Source: Jobdori self-dogfood 2026-04-09; observed in #clawcode-building-in-public across multiple Clawhip nudge cycles.