fix(cursor-agent): ingest workspace-less CLI transcript layout

[ozymandiashh]

Summary

The Cursor Agent source reported $0.00 for sessions that were really run through cursor-agent. The cause is a transcript layout that discovery did not recognize. This PR teaches the provider to ingest the workspace-less CLI layout while keeping the existing layouts intact.

Problem

cursor-agent invoked outside of a workspace does not write its transcript under a per project folder. It writes to a shared location:

projects/agent-transcripts/<uuid>/<uuid>.jsonl

Discovery only looked for projects/<projectId>/agent-transcripts/, so these workspace-less sessions were never picked up and their usage never counted.

Note that the two Cursor entries in the dashboard are by design: the Cursor IDE provider (reads the IDE's state.vscdb) and the Cursor Agent CLI provider (reads ~/.cursor) are separate sources and stay separate. This PR only fixes the CLI reader.

What this PR does

• Recognizes the workspace-less layout: when a project entry is itself the agent-transcripts directory, its transcripts are ingested directly.
• Preserves the normal per project layout: any other project entry still requires its own <projectDir>/agent-transcripts/, and discovery skips the entry when that folder is absent.

Correctness notes

• Discovery never scans a workspace storage root. Only an entry that is literally agent-transcripts, or a project that contains an agent-transcripts subfolder, is read. This is deliberate: scanning the storage root would sweep up unrelated top level files (extension state, crash logs, telemetry .txt) and misattribute them as transcripts.
• Within a session's UUID directory, both a .jsonl and a .txt can exist for the same conversation. The reader groups files by stem and selects the .jsonl when present, skipping the sibling .txt, so a single conversation is not counted twice.

Tests

• Regression 1: a workspace root that contains a top level .txt but no agent-transcripts directory yields no sources (no accidental ingestion).
• Regression 2: a UUID transcript directory containing both .jsonl and .txt for the same session yields exactly one entry, the .jsonl.
• Both fail before the change and pass after.
• npm test: full suite green. npm run build: ok. tsc --noEmit: clean.

Scope

Touches only src/providers/cursor-agent.ts and tests/providers/cursor-agent.test.ts. The Cursor IDE provider, the two-source design, and the dashboard are untouched.