feat: agent-native CLI fixes (F1, F7, F8)

[AlephNotation]

Three top-priority agent-native-CLI fixes, sourced from Trevin Chow's 10 Principles for Agent-Native CLIs and Cloudflare's Wrangler vocabulary rules. Implemented by three Opus 4.7 subagents in parallel git worktrees, then merged onto this integration branch.

What changed

--format json → --json (canonical Cloudflare/Wrangler vocabulary)

19 cobra --format string flags now have a sibling --json BoolVar. The old --format flag is preserved as a hidden, deprecated alias for backwards compat.

• New presenters.ParseFormat(quiet, json, format) centralizes precedence: quiet > json > format > default.
• Invalid --format values now error with an enumerated message instead of silently falling through:

  Error: --format must be "json" (got: "yaml"). Note: --format is deprecated, use --json instead
  

• vers status --format json still works but emits Flag --format has been deprecated, use --json instead to stderr (cobra MarkDeprecated).

vers info → vers get (verb consistency)

repo get and tag get already use the canonical verb. The top-level vers info was the inconsistent outlier. Renamed cmd/info.go → cmd/get.go via git mv; info is preserved as a cobra alias so existing scripts and integration tests keep working.

Pagination + truncation hints on every list command

Added --limit N (default 50; 0 = unbounded) and --offset N to status, commit list, repo list, repo tag list, tag list, env list, and alias (no-arg list mode).

JSON output shapes:

• Not truncated — bare items array (backwards-compatible).
• Truncated — envelope with hint:

  {
    "items": [...],
    "total": 11, "limit": 3, "offset": 0,
    "truncated": true, "next_offset": 3,
    "hint": "showing 3 of 11 — use --limit=N (0 for all) or --offset=3 for the next page"
  }

Text/quiet modes print the truncation hint to stderr so stdout stays clean for piping. New internal/presenters/pagination.go exposes PageInfo, ApplyPaging, PrintListJSON, PrintTruncationHint. Unit tested with 10 sub-cases.

Caveats and follow-ups

1. Pagination is client-side. vers-sdk-go v0.1.0-alpha.32 does not yet expose Limit/Offset query params (the response shapes include them). Inline // TODO: comments at every call site mark the migration path.
2. env list JSON shape changes only when truncated: {items: [{key, value}, ...]} to preserve order across pages. Bare object map is preserved when not truncated. MCP/agent consumers depending strictly on the map form will see the new shape only on the truncated branch.
3. Pre-existing integration tests in test/single-action/ fail on both this branch and main (verified via stash). Failures are unrelated to this PR — TestCommitAndList rejects vers commit <vm-id> because cobra treats the positional VM-ID as an unknown subcommand. Worth a separate finding/fix.

Validation

• make build — clean
• go vet ./... — clean
• go test ./internal/... ./cmd/... — all packages pass (including new format_test.go and pagination_test.go cases)
• Live smoke tests against an authenticated environment confirm --json, --limit/--offset, deprecation warnings, and the info alias all behave correctly.