feat: add bootcamp cache list to inspect cache contents

[Arthur742Ramos]

The gap

Today bootcamp cache lets you prune or clear the analysis cache — but there's no way to see what's actually in it. That makes cache hygiene blind: you can't tell which repos/phases/SHAs are cached, how big the cache is, or whether a stale entry is from your last run or three months ago. The classic "huh, my disk is full" surprise.

What this adds

bootcamp cache list (alias ls):

Human-readable table:

Cache directory: /Users/foo/.cache/repo-bootcamp
Cache version:   2

REPOSITORY                PHASE     SHA      AGE   SIZE    MODEL              STYLE
owner/example             facts     facebea  2h    24 kB   claude-opus-4-5    oss
owner/example             deps      facebea  2h    8.0 kB  claude-opus-4-5    oss
facebook/react            facts     def5678  1d    150 kB  claude-opus-4-5    corporate
(malformed) stray.json    -         -        3d    128 B   -                  -

Total: 4 entries, 182 kB

--json for scripting:

{
  "dir": "/Users/foo/.cache/repo-bootcamp",
  "version": 2,
  "entries": [
    { "file": "...", "path": "...", "sizeBytes": 24576, "mtimeMs": 1717248000000,
      "ageSeconds": 7200, "problem": null,
      "entry": { "version": 2, "phase": "facts", "repoFullName": "owner/example",
                 "commitSha": "facebead123456789012", ... } }
  ],
  "totalEntries": 4,
  "totalBytes": 186112
}

Always valid JSON, even when the cache is empty.

Design notes

• Problem entries are surfaced, not hidden. (legacy) for older-schema files, (malformed) for parse errors or wrong shape, (unreadable) for IO errors. Hiding stale disk usage was exactly the problem the command exists to solve.
• Shape validation matches readPhaseCache. Missing generationOptions normalizes to empty strings so readable v2 entries don't get falsely flagged as malformed — the existing reader is lenient here, the lister is too.
• Per-file errors are isolated. One bad file can't fail the listing; each file is summarized independently.
• mtime, not createdAt. Age and sort use filesystem mtime so the table aligns with what prune does (prune is also mtime-based). createdAt is still exposed in --json.
• SHA truncated to 7 chars in the table, full SHA in JSON. Same convention as git's --oneline.
• Pure renderer module. All formatting helpers live in src/commands/cache-list.ts and are unit-tested directly without spawning a CLI process.
• Exports getCacheVersion() to stop tests and the CLI from duplicating the CACHE_VERSION = 2 constant.

Tests

• 20 new unit tests (test/cache.test.ts + test/cache-list.test.ts): empty/missing dir, valid v2 entries with full metadata, JSON parse errors flagged as malformed, valid JSON with wrong shape flagged as malformed, version-mismatch flagged as legacy, missing generationOptions accepted (mirrors readPhaseCache), mtime-desc sort with deterministic filename tiebreaker, byte/age formatters across all ranges, JSON shape stability.
• 2 new e2e tests in test/e2e/cache-command.e2e.test.ts: populated cache with a valid entry + stray blob → assert both human and JSON output; missing cache dir → assert empty-message + empty JSON. Both use the existing temp HOME redirect that PR fix: make path checks and tool output cross-platform on Windows #32 made work cross-platform.

Validation

Check	Before	After
typecheck	✓	✓
lint	✓	✓
unit tests	965/965	985/985
CLI e2e	9/9	11/11
build	✓	✓

Process note

I ran the plan past the rubber-duck before implementing. Key adoptions:

• E2E writes raw JSON into the temp home cache dir (not via writePhaseCache from the test process — those don't share CACHE_DIR after module load).
• --json always emits valid JSON, even when empty.
• Exported getCacheVersion() instead of duplicating 2.
• Aligned shape validation with readPhaseCache's leniency around generationOptions.
• Used mtime (not createdAt) so age/sort match prune semantics.

Not in scope

• --sort <field> flag. Default newest-first is the right v1; easy to add later if asked for.
• Hard upper bound on file size during parsing. Cache files are KB each; not worth the complexity unless something concrete points the other way.