fix(fm-spawn): forward Anthropic API env vars to crewmate panes for Pioneer/TokenRouter lanes

[jwalin-shah]

Intent

Forward ANTHROPIC_API_KEY, ANTHROPIC_BASE_URL, and model discovery env vars (ANTHROPIC_DEFAULT_OPUS_MODEL, ANTHROPIC_DEFAULT_SONNET_MODEL, ANTHROPIC_DEFAULT_HAIKU_MODEL) from firstmate's environment into the crewmate launch command in bin/fm-spawn.sh, so crewmates authenticate against the correct provider for Pioneer/TokenRouter lanes. The existing CLAUDE_CONFIG_DIR forwarding for the claude harness is preserved unchanged.

What Changed

• bin/fm-spawn.sh: Forward ANTHROPIC_API_KEY, ANTHROPIC_BASE_URL, ANTHROPIC_DEFAULT_OPUS_MODEL, ANTHROPIC_DEFAULT_SONNET_MODEL, and ANTHROPIC_DEFAULT_HAIKU_MODEL from firstmate's environment into the crewmate launch command, so crewmates authenticate against the correct provider for Pioneer/TokenRouter lanes. Only prepended when the corresponding env var is set; unset values are skipped. The existing CLAUDE_CONFIG_DIR forwarding for the claude harness is preserved unchanged.
• tests/fm-spawn-dispatch-profile.test.sh: Pin all five ANTHROPIC_* env vars to empty in run_spawn() to prevent env-leak flakiness from the developer's shell. Add three new tests covering the forwarding behavior: when vars are set (all harnesses), when vars are unset (no prefix emitted), and verification that forwarding applies to all harnesses, not only claude.

Risk Assessment

✅ Low: Change is well-bounded, follows existing patterns, has good test coverage, and fully conforms to the stated user intent.

Testing

Ran the full fm-spawn-dispatch-profile test suite (28 tests). All passed, including the 3 new tests for ANTHROPIC_* env var forwarding (set, unset, and all-harnesses cases) and the 3 existing CLAUDE_CONFIG_DIR tests confirming the existing behavior is preserved. The evidence file is at /var/folders/sj/b3pb98ls4mx03dx50srzyq380000gn/T/no-mistakes-evidence/01KYX34J92A4GH76FWE1M1HTAB/fm-spawn-dispatch-profile-test-output.txt.

Evidence: Full test suite run

ok - no --model/--effort records defaults and types the claude launch instructions
ok - relative home overrides ignore CDPATH and become absolute before spawn launch construction
ok - FM_HOME defaults resolve relative paths and preserve absolute spellings
ok - absolute override spellings are preserved in spawn launch paths
ok - unresolvable relative spawn overrides fail with named diagnostics
ok - active crew-dispatch profile requires an explicit harness for ship spawns
ok - active crew-dispatch profile requires an explicit harness for scout spawns
ok - active crew-dispatch profile allows an explicit resolved harness
ok - active crew-dispatch profile allows the legacy positional harness form
ok - active crew-dispatch profile allows the raw launch-command escape hatch
ok - claude receives --model and --effort profile flags
ok - codex receives --model and model_reasoning_effort profile flags
ok - codex omits unsupported max effort instead of passing a bad config value
ok - grok receives --model and --reasoning-effort profile flags
ok - grok omits unsupported max reasoning effort
ok - grok omits unsupported xhigh reasoning effort
ok - opencode receives --model and omits the unsupported effort axis
ok - pi receives --model and --thinking max profile flags
ok - pi-signed shares Pi launch semantics while preserving its configured and recorded identity
ok - pi-signed refuses safely and actionably when the selected executable is unavailable
ok - pi-signed is a distinct persistent secondmate runtime with shared Pi supervision semantics
ok - batch dispatch forwards shared --harness, --model, and --effort to every pair
ok - claude forwards firstmate's CLAUDE_CONFIG_DIR so the crewmate uses the same credential store
ok - claude omits the config-dir prefix when firstmate runs with the single-store default
ok - non-claude harnesses do not receive the claude CLAUDE_CONFIG_DIR prefix
ok - active crew-dispatch profile does not block secondmate launches
ok - claude forwards firstmate's ANTHROPIC_* env vars so the crewmate authenticates against the same provider
ok - claude omits the ANTHROPIC_* env prefix when firstmate runs with default credentials
ok - ANTHROPIC_* env vars are forwarded for all harnesses, not just claude
# all fm-spawn-dispatch-profile tests passed

Pipeline

Updates from git push no-mistakes

✅ **intent** - passed

✅ No issues found.

✅ **Rebase** - passed

✅ No issues found.

✅ **Review** - passed

✅ No issues found.

✅ **Test** - passed

✅ No issues found.

• bash tests/fm-spawn-dispatch-profile.test.sh

✅ **Document** - passed

✅ No issues found.

✅ **Lint** - passed

✅ No issues found.

✅ **Push** - passed

✅ No issues found.