feat(loop-context): track daily token spend across runs, add --on-exceed hook

[KhaiTrang1995]

Summary

--budget-from-pattern (previous PR) only guards a single run's ledger.
loop-budget.md's daily table ("Max tokens/day") is a cross-run cap that
nothing enforced, and its "On budget exceed" section is still a manual
3-step checklist (pause schedulers, log the event, open an issue).

What

• --daily-budget-from-pattern <id>: accumulates the newest ledger attempt's
  tokensUsed into a per-pattern state file
  (.loop-context/daily-spend.<pattern>.json, rolling over at UTC midnight)
  and escalates with a new trigger daily-budget once the running total
  reaches loop-cost's suggestedDailyCap -- but only if no per-run trigger
  (stagnation, no-progress, token-budget, max-iterations) already fired;
  those always take priority.
• --daily-state-dir <dir> (default .loop-context): where that state file
  lives.
• --on-exceed <script>: on any escalate, pipes the BreakerDecision as
  JSON to the script's stdin -- a scriptable replacement for
  loop-budget.md's manual checklist. Fire-and-forget: the script's exit
  code doesn't change --check's own.
• Reused the existing --budget-level/--budget-cadence/
  --budget-conservative flags for the daily lookup rather than adding
  parallel ones.
• Updated the loop-guard skill template and loop-context's README with
  the new flags and an example wiring both the per-run and daily budgets
  together.

Why this shape

• context-manager.ts's checkCircuitBreaker stays pure and dependency-free
  -- the daily check and state file live in a new daily-spend.ts module and
  the CLI layer, mirroring how budget-resolver.ts was kept separate from
  it in the previous PR.
• daily-budget is an additive member of the existing BreakerTrigger union,
  so no existing consumer of BreakerDecision breaks.
• --on-exceed is intentionally dumb (JSON on stdin, no retry/backoff) to
  avoid growing into a job-runner -- operators write the actual pause/log/
  notify logic.

Tested

tools/loop-context: 43/43 passing after a fully clean rebuild (wiped
node_modules/dist, reinstalled, rebuilt). tools/loop-cost (the
dependency this shells out to): 12/12 passing after the same clean rebuild.
12 new tests: daily-spend state module (fresh start, accumulation,
per-pattern isolation, stale-date rollover, persistence),
resolveDailyBudgetFromPattern (returns the daily cap, at least covers one
run, surfaces loop-cost's unknown-pattern error), and CLI integration
(escalates once the daily cap is reached, does not override an existing
per-run trigger, --on-exceed receives the decision JSON on escalate, and is
not invoked when the run continues). All pre-existing tests pass unmodified.
Version 1.1.0 -> 1.2.0.