Harden occurrence pipeline, strengthen type design

[yairfalse]

Summary

• Fix silent data loss in occurrence pipeline: Replace overbroad rescue with explicit error handling — Occurrence.new failures raise with diagnostics, persist/2 errors are logged, all LogEmitter return values are checked
• Strengthen type invariants: Add @enforce_keys to Result and Events, narrow strategy from atom() to :direct | :canary | :blue_green, add Result.rolledback/5 factory, define NodeKind.t() type
• Close test gaps: Fix conditional if File.exists? assertion in integration test, add build_entity edge case tests, persist error path test, clean up leaked emitter processes

What was found

Four review agents (code reviewer, silent failure hunter, type design analyzer, test coverage analyzer) identified 17 issues ranging from critical silent data loss to minor type narrowing. All addressed in this PR.

Test plan

• 265 tests passing, 0 failures (+5 new tests)
• mix compile --warnings-as-errors clean
• mix format --check-formatted clean
• mix credo — no new issues (pre-existing Logger metadata warnings only)
• Sykli pre-commit: all 5 tasks green

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR hardens the deployment occurrence pipeline and tightens type invariants across deploy results, events, and graph nodes, while adding tests to cover edge cases and prior silent-failure paths.

Changes:

• Replace overbroad exception handling around occurrence generation with explicit error handling and improved diagnostics/logging.
• Strengthen type invariants via @enforce_keys, narrower strategy types, a rolledback/5 result constructor, and a dedicated NodeKind.t() type.
• Expand test coverage for malformed resource inputs, occurrence persistence failure paths, integration assertions, and emitter process cleanup.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
test/nopea/occurrence_test.exs	Adds edge-case tests for entity building and a persist error-path test.
test/nopea/occurrence_log_test.exs	Ensures emitter processes are stopped on test exit to prevent leaks.
test/nopea/deploy_integration_test.exs	Makes occurrence-file assertion unconditional to avoid silent pass.
test/nopea/deploy/result_test.exs	Adds tests for rolledback/5 and @enforce_keys behavior.
lib/nopea/occurrence.ex	Makes Occurrence.new/… failure explicit (raise) and widens start_log_emitter/1 spec to include error tuples.
lib/nopea/graph/node_kind.ex	Introduces NodeKind.t() as a constrained type.
lib/nopea/graph/node.ex	Narrows Node.kind type to NodeKind.t().
lib/nopea/events/emitter.ex	Logs a debug message when emission is ignored due to disabled emitter.
lib/nopea/events.ex	Adds @enforce_keys to event struct for stronger invariants.
lib/nopea/deploy/spec.ex	Narrows Spec.strategy type to the constrained Result.strategy().
lib/nopea/deploy/result.ex	Adds strategy type, enforces required keys, and adds rolledback/5 constructor.
lib/nopea/deploy.ex	Improves occurrence persistence handling and checks LogEmitter return values with explicit logging.

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[Copilot]

Node.t/0 now narrows kind to NodeKind.t(), but new/3 is still spec’d as taking atom() and is only guarded by is_atom(kind) (with a runtime NodeKind.valid?/1 check). To keep the public types consistent for Dialyzer/docs, update @spec new/3 (and ideally the guard) to accept NodeKind.t() rather than atom().