feat: structured logging via nova_jsonlogger tier1 + claude-try auto-request

[Taure]

Summary

Combines three small but related changes since they all touch the logging or post-triage chain:

1. Revert io:format debug → structured ?LOG_*

triagebot_webhook_controller reverts the temporary io:format escape hatch (added in v0.1.7 to debug the webhook-secret mismatch when nova_jsonlogger silently dropped the diagnostic maps) back to structured ?LOG_ERROR / ?LOG_WARNING / ?LOG_INFO calls. The root cause is now fixed upstream — see #2.

2. Pin nova to the jsonlogger tier1 PR fork

Nova dep moves to Taure/nova at branch feat/jsonlogger-tier1 (the head of novaframework/nova#385). The tier1 jsonlogger:

• Extracts class / reason / stacktrace meta into a structured error object per schema
• Applies max_term_size and max_string_length caps so a gnarly stacktrace can't blow the log line
• Adds schema presets (we pick ecs)

rebar.config carries a TODO to swap back to a tag once the upstream PR lands and a release is cut.

3. ECS schema + caps in prod_sys.config.src

Opts into the tier1 features:

formatter => {nova_jsonlogger, #{
    schema => ecs,
    map_depth => 3,
    term_depth => 50,
    max_term_size => 8192,
    max_string_length => 8192
}}

Also drops logger_level from debug back to info now that the debugging round is over.

4. Auto-request @claude implement when claude-try is applied

In triagebot_runner, after apply_labels succeeds, if claude-try is in the proposed label set, post a follow-up @claude please implement this issue per the triage above. Open a PR closing this issue when done. comment. The claude-code-action workflow in the target repo (Taure/gakudan/.github/workflows/claude.yml) already listens on @claude mentions, so this closes the loop without needing a maintainer to manually re-apply the label.

Test plan

• rebar3 fmt --check
• rebar3 xref
• rebar3 dialyzer (clean)
• rebar3 ct 20/20
• After deploy: trigger a webhook on the gakudan repo and confirm a structured event: webhook_received line appears in Clever Cloud logs under the ECS schema (i.e. with @timestamp, log.level, message fields)
• Force a verify_signature crash and confirm the error object renders with type / reason / stacktrace per ECS
• Trigger a claude-try label proposal and confirm an @claude follow-up comment lands on the issue

[github-actions]

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