feat(cli): build the ccas subcommand tree (#46)

[Sootopolis]

Closes #46.

Turns the ccas binary from a serve-only stub into a real CLI — a zio-cli command tree dispatched as a thin HTTP client to the local CcasServer.

Commands

serve, membership, history, recruit, stats, jobs, logs, blacklist {add,list,remove}, schedule {list,add,remove}, with a global --server (default http://127.0.0.1:8080). Job commands submit to the existing /api routes and poll GET /api/jobs/{id} to completion. Exit codes: 0 Completed, 1 Failed / submission error / unreachable server, 2 usage error.

Notable decisions

• zio-cli, not decline — ZIO-native (no cats), plus built-in shell-completion generation (towards Shell completions for ccas #49). Aligns deps: zio 2.1.24→2.1.26, zio-json 0.9.0→0.9.2 for zio-cli 0.8.1.
• Wire DTOs as the single source of truth — request/response case classes in JobRoutes/ScheduleRoutes/BlacklistRoutes widened private[server]→private[ccas] so the CLI imports them directly (compile-time drift safety, no duplicated codecs).
• Bounded poll loop — 60-min cap, unknown status treated as terminal, friendly "start a server with 'ccas serve' first." on connection refusal.

Deferred (forced — need server routes / other issues)

admin ref/clubdata (no routes / would duplicate matchref), __complete dynamic completions (#49), config.toml resolution (#43), live log tail (#47 — logs polls status for now).

Verification

• sbt test green (772/772), incl. all route suites (the DTO visibility widening doesn't break them).
• New CLI suites: TestCliParser, TestJobPoller, TestCcasApiClient (19 tests).
• Staged binary: --help (exit 0), bad command (exit 2), unreachable server (exit 1, friendly message); bounded e2e against a local ccas_test server — real round-trips, correct exit codes.

Known caveat

zio-cli is POSIX-style (options before positional args); options after a positional are silently dropped/swallowed. Documented in CliCommand's scaladoc and each --help. Follow-up tracked in #70 (unify app + CLI parsing), and an upstream zio-cli issue is drafted.

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