Distinguish a source that was never attempted from one that was attempted and failed #708

Problem

When a source's download fails, the end-of-run cache report still lists it under "Not fetched, skipped" — the identical wording used for a source that --only deliberately excluded. A run where every source failed prints the per-source failures and then a line saying those same sources were skipped, which reads as though nothing was tried.

The report is describing disk state (no payload present), but the wording claims an intent.

Observed — both sources were attempted and both failed:

✗ core: fetch failed while downloading "file" — continuing with remaining sources
✗ organisms: fetch failed while downloading "file" — continuing with remaining sources
  Not fetched, skipped: core, organisms
✗ Fetch incomplete: 2 of 2 sources failed (core, organisms)

Potential solution(s)

• Separate the two states in the report — excluded by the run's scope, versus attempted and failed
• Or drop failed sources from the skipped line entirely, since the failure was already reported directly above it

Acceptance criteria

• A source that failed its download is never described as skipped
• A source excluded by --only is still reported as not fetched
• A run where every source failed does not print a line implying no attempt was made

Case data

• Workspace: fm — during a fetch
• Territory: cli
• Impacted file(s): packages/cli/src/commands/FetchCommand.ts (reportCache)
• Size: xs

Implementation details are tracked internally.