feat(economy): enterprise-aware mode (Bedrock/Vertex/OTEL) with USD-saved estimate

[jhonatanjunio]

Closes #5

Summary

On Anthropic's usage-based enterprise plans there is no included token allowance — every token is billed at API rates and an admin-set spend cap pauses the workspace when hit (requires a manual refill ticket). This PR makes that economics visible inside squeez.

What changed

• New module src/economy/enterprise.rs — env-var detection (Bedrock, Vertex, OTEL) + USD-savings estimator at Anthropic's public Sonnet 4.6 and Opus 4.7 rates. Zero new deps, no network calls.
• Wrap header gains [squeez: enterprise=<slug>] when a transport is detected.
• Init banner prints an enterprise hint, including USD saved in the prior session when available.
• New MCP tool squeez_enterprise_savings returns mode + saved tokens + USD at both Sonnet and Opus rates — finance dashboards and the agent itself can quote a number.

How detection works

Env var	Mode
CLAUDE_CODE_USE_BEDROCK=1 or AWS_BEDROCK_REGION	bedrock
CLAUDE_CODE_USE_VERTEX=1 or ANTHROPIC_VERTEX_PROJECT_ID	vertex
OTEL_EXPORTER_OTLP_ENDPOINT / OTEL_METRIC_EXPORT_INTERVAL / CLAUDE_CODE_ENABLE_TELEMETRY=1	otel
nothing	none (no banner, no tag)

Precedence: Bedrock > Vertex > OTEL.

Verification

$ CLAUDE_CODE_USE_BEDROCK=1 \
  echo '{"jsonrpc":"2.0","id":1,"method":"tools/call",\
"params":{"name":"squeez_enterprise_savings","arguments":{}}}' \
  | ./target/release/squeez.exe mcp
{"jsonrpc":"2.0","id":1,"result":{"content":[{"type":"text","text":"{
  \"enterprise_mode\":\"bedrock\",
  \"is_enterprise\":true,
  \"tokens_saved_session\":2,
  \"usd_saved_sonnet46\":0.000006,
  \"usd_saved_opus47\":0.000010
}"}]}}

Tests

11 new unit tests:

• 6 detection paths (Bedrock via flag, Bedrock via region var, Vertex via flag, Vertex via project ID, OTEL via endpoint, empty env)
• Precedence (bedrock_beats_otel_when_both_set)
• Truthy/falsy parsing (falsy_use_flag_is_not_enterprise)
• Pricing math against published rates
• Header tag rendering (empty when not enterprise)
• Init banner rendering with/without prior savings

Full lib suite: 170/170 passing (159 prior + 11 new).

Design choices

• No network calls — detection is env-var only, and we never read credentials.
• Conservative pricing — Sonnet rate by default. Enterprise contracts often have negotiated discounts, so our number is at worst slightly overstated for fully discounted contracts and at best a fair on-demand-parity floor for everyone else.
• Out of scope: enforcing or reporting to OTEL collectors (would couple us to a transport), per-key spend caps (those live on Anthropic's side).

[jhonatanjunio]

Superseded by upstream PR — moved to claudioemmanuel/squeez. See README of this fork for the upstream link.