Remove init dep from multisig mods

[andrew-fleming]

Resolves #611

This PR ignores Forwarder.compact because it will removed. Depends on #566

Summary by CodeRabbit

• Refactor

  • Multisig contract suite refactored to manage initialization state internally, removing reliance on external helper modules while maintaining initialization enforcement semantics.

• Tests

  • Updated initialization guard test assertions to reflect new contract-specific error messages.

• Chores

  • Optimized build pipeline task dependencies for multisig compilation.

[coderabbitai]

Walkthrough

Three multisig compact modules (Signer, Forwarder, ForwarderPrivate) drop their dependency on the shared Initializable module. Each gains an exported _isInitialized: Boolean ledger and local assertInitialized/assertNotInitialized guard circuits. All initialization call sites and tests are updated accordingly, and turbo.json removes the compact:security build dependency from compact:multisig.

Changes

Per-module initialization guard refactor

Layer / File(s)	Summary
Local _isInitialized ledger and guard circuits contracts/src/multisig/Signer.compact, contracts/src/multisig/Forwarder.compact, contracts/src/multisig/ForwarderPrivate.compact	Each module exports a new _isInitialized: Boolean ledger and defines internal assertInitialized() and assertNotInitialized() circuits that emit module-prefixed error messages, replacing the shared Initializable dependency.
Circuit call-site updates to use local guards contracts/src/multisig/Signer.compact, contracts/src/multisig/Forwarder.compact, contracts/src/multisig/ForwarderPrivate.compact	initialize, assertSigner, assertThresholdMet, getSignerCount, getThreshold, _depositShielded, _depositUnshielded, _deposit, and _drain replace Initializable_* calls with the new module-local guards and direct _isInitialized = true assignment.
Test error message updates and build config contracts/src/multisig/test/Signer.test.ts, contracts/src/multisig/test/Forwarder.test.ts, contracts/src/multisig/test/ForwarderPrivate.test.ts, turbo.json	Expected error strings in tests change from Initializable: ... to Signer:/Forwarder:/ForwarderPrivate: prefixes; turbo.json drops compact:security from compact:multisig's dependsOn.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• OpenZeppelin/compact-contracts#424: Originally added the multisig Signer.compact module using the Initializable-based init guard that this PR replaces.
• OpenZeppelin/compact-contracts#526: Introduced Forwarder.compact and ForwarderPrivate.compact with the Initializable_* init gating pattern being removed here.
• OpenZeppelin/compact-contracts#562: Applied the same per-module _isInitialized ledger pattern to other modules, establishing the approach this PR follows for the multisig suite.

Suggested labels

enhancement

Suggested reviewers

• 0xisk

Poem

🐇 Hop hop, no more shared init to borrow,
Each module carries its own Boolean flag!
assertInitialized guards each tomorrow,
No Initializable chains left to drag.
The rabbit's done untangling the code —
Each contract now owns its own tidy road! 🥕

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'Remove init dep from multisig mods' directly and clearly describes the main objective of the PR - removing the initializable dependency from multisig modules.
Linked Issues check	✅ Passed	The PR successfully removes the Initializable dependency from all three multisig modules (Forwarder, ForwarderPrivate, Signer) by introducing internal initialization tracking via _isInitialized ledger and local guard circuits.
Out of Scope Changes check	✅ Passed	All changes are directly related to removing the Initializable dependency. The turbo.json change to remove compact:security dependency appears related to breaking the initialization dependency chain.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[0xisk]

LGTM!