feat: add tuskd daemon for continuous rule evaluation

[Fraser-Isbester]

Summary

• Adds cmd/tuskd/main.go — a separate binary that runs the rule engine as a polling daemon without any TUI dependencies (no tview/tcell linked)
• Reuses existing internal/rules, internal/db, and internal/config packages with zero changes
• Adds build:daemon and daemon tasks to Taskfile

Why a separate binary?

Go compiles each main package independently. Since cmd/tuskd never imports internal/tui, the linker drops tview/tcell entirely:

$ go list -deps ./cmd/tuskd | grep -E 'tview|tcell'
(empty — no TUI deps)

$ ls -lh tusk tuskd
-rwxr-xr-x  28M tusk
-rwxr-xr-x  26M tuskd

Usage

# Run with a profile
tuskd -P prod

# Custom polling interval
tuskd -P prod --interval 5s

Test plan

• go build ./cmd/tusk && go build ./cmd/tuskd — both compile
• go list -deps ./cmd/tuskd | grep -E 'tview|tcell' — returns nothing
• task test — all 70 tests pass unchanged
• task daemon against a live dev DB with rules configured

[Fraser-Isbester]

Superseded by #9, which lands the same cmd/tuskd binary with added failure handling (per-resource fetch errors logged and skipped rather than crashing the loop), a testable poll-loop seam, unit tests, and a systemd example. Closing in favor of that. The build:daemon/daemon Taskfile targets from this branch are worth porting separately.