fix: consolidation batch failure must not report a succeeded job

[chrlesur]

Closes #32

Context

Production incident (2026-07-08, space terraform-provider): the LLMaaS backend rejected every consolidation call (context-length error), yet bank_consolidate jobs ended succeeded with notes_processed=0 and batches=0/50. The failure stayed invisible for 6 days. The root cause of the LLM rejection itself was an infrastructure misconfiguration (handled separately on the LLMaaS side); this PR fixes the Live Memory reporting bug that masked it.

Changes

consolidator.py — consolidate() now tracks the first batch failure (LLM or bank write) instead of silently breaking out of the loop:

• ok — no failure (unchanged contract);
• error — failure with 0 completed batches (nothing was integrated);
• partial — failure after ≥1 applied batch (work was integrated and the corresponding notes deleted; metrics preserved);
• failed runs expose failed_batch and a message embedding the upstream error plus the number of notes left in live/.

consolidation_queue.py — the worker already mapped any non-ok status to a failed job with result.message as error; the lane phase now reflects the real outcome (done/failed) instead of always displaying done.

config.py — fail fast at startup when LLMAAS_MAX_TOKENS >= LLMAAS_CONTEXT_WINDOW: such a budget can never produce a valid call on a large prompt.

Tests

• tests/test_consolidation_batch_failure.py (7 tests) replays the incident: first batch rejected with the real 262144 context-length error → asserts status="error", zero metrics, _meta.json untouched, no bank write attempted, and end-to-end through the queue a failed job with an exploitable error. Partial-failure and full-success non-regression paths covered.
• tests/test_config.py::TestLlmBudgetCoherence (4 tests) for the startup guard.
• Adversarial check: with the fix reverted (git stash on src/), 6 of the new tests fail on the original code — they bite, they don't rubber-stamp.
• Full suite: 424 passed + 1 xfailed (baseline was 413 + 1).

Validation plan (post-merge, production)

1. Redeploy, then re-run bank_consolidate(space_id="terraform-provider") (107 pending notes).
2. Expect notes_processed > 0, llm_tokens_used > 0, live.notes_count decreasing, last_consolidation updated.
3. Counter-check: a forced LLM failure must now end the job failed with the upstream message — never a silent empty succeeded.