Beacon Atlas: pulse new contract connections

[SageHaven]

Summary

• add a short-lived additive glow whenever a new Beacon Atlas contract line is created
• drive three visible beats through a deterministic 2.4-second animation envelope
• dispose temporary geometry and material at the deadline or when the contract is removed
• preserve the persistent contract line's existing state color, opacity, highlighting, and particle flow

Bounty acceptance criteria

• Contract animations — pulse/glow when new contracts are created: addContractLine() now starts a dedicated glow line immediately after adding the persistent connection.
• Bounded animation: contractPulseFrame() returns deterministic opacity/scale frames and marks the pulse disposable after 2.4 seconds.
• Safe lifecycle: expired and explicitly removed contract pulses release their Three.js geometry and material.
• Focused scope: this PR changes only the connection renderer, the pulse helper, and matching deterministic tests; it claims no other Beacon Atlas track.

Validation

• node --check site/beacon/connections.js && node --check site/beacon/contract-pulse.mjs — PASS
• node --test tests/beacon_contract_pulse.test.mjs — PASS, 4 tests
• python3 -m unittest -v tests.test_beacon_contract_animations — PASS, 3 tests
• python3 -m unittest -v tests.test_beacon_atlas — PASS, 14 tests
• python3 -m unittest -v tests.test_beacon_atlas_behavior — PASS, 31 tests
• git diff --check — PASS

Limitations

• Chrome, Firefox, and mobile Safari are not installed on the VPS, so manual WebGL rendering was not claimed.
• The existing behavior suite emits SQLite ResourceWarning messages after its 31 passing tests; this focused frontend change does not alter that database lifecycle.

Bounty: Scottcjn/rustchain-bounties#1524 — Track B, Contract animations (10 RTC).

Payout: RTC on RustChain — RTC90182c386cc09a24c03ffd58e62c39ac4ea750bc

Implemented and validated with autonomous AI assistance under the @SageHaven agent identity.

[github-actions]

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