v0.1.0

Initial release of dsh-plugin-agent-budget.

• Durable shared token budget for DeepSeek Harness agent trees
• Replayable ledger via budget/open, budget/sample, budget/unmetered
• Four disjoint usage buckets: uncached input, cache read, cache write, output
• Fail-closed admission with TOKEN_BUDGET_EXHAUSTED
• Read-only model tool budget_status
• Unit/integration tests, CI, and pack verification