fix: forward --tail flag in rtk docker compose logs

[slice-mihird]

Problem

docker compose logs --tail=20 web rewrites correctly to rtk docker compose logs --tail=20 web, but clap had no --tail field on the Logs subcommand. This caused clap to fall through to Other(args) → run_compose_passthrough → 0% token savings, defeating the rewrite.

Additionally, run_compose_logs always fetched the last 100 lines regardless of what the user requested, silently ignoring their preference.

Solution

• Add #[arg(long, default_value_t = 100)] tail: u32 to ComposeCommands::Logs
• Forward the value to run_compose_logs(service, tail, verbose)
• Use tail in the --tail arg passed to docker (was hardcoded "100")

Default is unchanged (100 lines), so existing behaviour is preserved for bare rtk docker compose logs.

Changes

• src/main.rs: add --tail to ComposeCommands::Logs, pass to handler
• src/container.rs: accept tail: u32, use in docker invocation, compile-time signature test

Before / After

# Before: falls to passthrough, 0% savings
rtk docker compose logs --tail=20 web   # ran docker compose logs --tail=20 web unfiltered

# After: filtered, ~80% savings
rtk docker compose logs --tail=20 web   # runs docker compose logs --tail 20 web → filtered output

Relates to #578.

🤖 Generated with Claude Code

[pszymkowiak]

Please retarget this PR to develop instead of master. We use develop as the integration branch — master is for releases only. You can change the base branch in the PR settings. Thanks!

[slice-mihird]

Done — retargeted to develop. Apologies for the wrong base!