perf: canonicalize internal equality assertions

[Kuhai9801]

Description

Canonicalize internal-variable equality assertions so equivalent wires share a representative instead of emitting an extra a - b == 0 constraint.

This reduces the issue #555 equality-heavy case by removing redundant equality constraints and internal wires where aliasing is valid.

Fixes #555

Type of change

• Optimization / performance improvement

How has this been tested?

• Added unit, frontend builder, and issue reduce constraint generated with api.AssertIsEqual(...) #555 regression coverage.
• Refreshed affected stats fixtures.
• Fork Actions issue555-proof: changed-surface tests and benchmark passed.
• Fork Actions issue555-full-proof: upstream short test block passed.
• Fork Actions pull_request/staticcheck: gofmt, goimports, generated-file check, and golangci-lint passed.

How has this been benchmarked?

• go test ./internal/regression_tests/issue555 -run '^$' -bench BenchmarkInternalEqualityCanonicalizationCompile -benchtime=100x -count=3

Benchmark result: R1CS and SCS equality-heavy paths match the baseline at 2048 constraints/op and 2048 internal_variables/op; aliasing adds one instruction.

Checklist:

• I have performed a self-review of my code
• I have added tests that prove my fix is effective or that my feature works
• I did not modify files generated from templates
• golangci-lint does not output errors locally
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

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Note

Medium Risk
Touches core compile/solve paths (instruction tree, witness assignment, serialization); safety relies on correct no-alias escapes for hints, commitments, and stored wire IDs.

Overview
Adds internal wire aliasing so AssertIsEqual between two unit-coefficient internal wires can record a union instead of emitting a - b == 0, cutting redundant constraints (issue #555).

R1CS and SCS builders track aliases via wirealias.Set (internal-only unions, MarkNoAlias for public/secret, hints, commitments, custom instruction outputs). During Compile, applyWireAliases calls System.ApplyWireAliases to rewrite constraint/hint calldata to canonical wire IDs, rebuild instruction levels, reset lookup-hint level caches, and append a BlueprintWireAliases solver instruction (no proof constraints) so eliminated wires get witness values from their representative.

Serialization registers the new blueprint type; stats reflect slightly lower Plonk constraint counts on several benchmarks.

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