feat: add Rite pipeline observability (COD-433)

[shivros]

Summary

Implements COD-433 observability for Rite:

• secret-free startup inventory for the listener, enabled sources, and handlers
• terse structured logs for webhook and Iris SSE events, matches, and action outcomes
• GET /status with event/action counters, uptime, and handler count

Verification

cargo test --all-targets
cargo clippy --all-targets -- -D warnings
cargo fmt --all -- --check

All passed locally.

Notes

events_matched counts events with one or more matching handlers; action counters retain per-handler outcome totals.

[shivros]

🤖 Automated Review Panel

GPT-5.6 (openai/gpt-5.5)

Initial review flagged three correctness/safety issues: events_matched was counting handlers rather than events; request-error logs could expose action URL secrets; and startup logs preceded configuration validation. All three were fixed before the final verification run. The reviewer confirmed the requested status fields and shared counter architecture otherwise aligned with COD-433.

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Gemini 3 Flash (google/gemini-3-flash-preview)

Initial review flagged the same counter-semantics issue: one event matching two handlers must produce one matched-event count, not two. Fixed before final verification: events_matched increments once only when an event has at least one matching handler.

Final local verification after fixes: cargo test --all-targets, cargo clippy --all-targets -- -D warnings, and cargo fmt --all -- --check all passed.

[shivros]

Auto-Merge Gate

Confidence: 0.91

COD-433 is a focused, goal-aligned observability change: secret-safe startup inventory, concise webhook/Iris event and handler outcome logs, and atomic process-local /status counters. The implementation includes the requested startup-summary and status-counter tests.

Checks observed: GitHub CI test passed; local cargo test --all-targets, cargo clippy --all-targets -- -D warnings, and cargo fmt --all -- --check passed on head 4c40907187bcfb900aadfec9d3bdc0f5b39b0bdb.

Scope limit: merge covers the code change only; it does not assert a live deployment or production event-flow verification.