fix(visualization): parse origins array for event highlighting

[MsfPablo]

Root cause

eventOriginFromSummary in src/visualization/coloring.ts scanned the commit body for /"origin"\s*:\s*"([^"]+)"/g — a singular "origin" string field accepting only "agent-edit" or "inline-completion".

But formatWindowCommitMessage in src/recording/staging-tracker.ts writes the assistant commit metadata as:

JSON.stringify({ ..., origins: commit.origins, ... })

commit.origins is the plural "origins" array of EditOrigin values ("assistant-inline-completion", "assistant-agent-chat", "assistant-tool-edit", "mixed", …). The singular regex never matched, so origins.size === 0 and every commit was classified "unknown", breaking the "Event type" coloring mode entirely.

Fix

Parse the "origins":[...] array instead of the singular field, and map each serialized EditOrigin value to its EventOriginKind:

• assistant-inline-completion → inline-completion
• assistant-agent-chat / assistant-tool-edit → agent-edit
• mixed → mixed
• everything else (assistant-unknown, human, …) → unknown

The existing contract is preserved: "unknown" is still returned when the field is absent (e.g. human commits), and "mixed" is returned when the array contains more than one distinct kind (after mapping, so two agent-edit origins collapse to agent-edit rather than mixed).

Verification

• npm run compile — clean (tsc -p .)
• npm run lint — 0 errors (13 pre-existing warnings in src/utils/paths.ts, untouched by this change)
• npm run test:unit — 42/42 pass, including 8 new tests in test/coloring.test.ts covering each mapping, the same-kind collapse, the distinct-kinds mixed case, and the absent-field unknown fallback.

Closes #5