wasmer 7.5 upgrade in experimental executor

[andrei-marinica]

Upgrades the experimental executor to Wasmer 7.5 and adds consistent WASM-local limits and metering.

Changes:

• Updates Wasmer dependencies and middleware lifetime APIs.
• Enforces a shared 4,000-local function limit.
• Adds boundary tests for both executors.

Had to re-create the PR after a wrong merge. Original impl: #93

[Copilot]

🟡 Changes recommended

Local metering can miscalculate costs when a 64-bit unmetered-local threshold is narrowed to u32, and the new metering path lacks coverage.

2 open findings

• Avoid truncating unmetered_locals from usize to u32 · New
• Test local metering with nonzero allocation cost · New

What changed in this PR

Upgrades the experimental executor to Wasmer 7.5 while aligning local limits and metering across executors.

Changes:

• Updates Wasmer dependencies and middleware lifetimes.
• Shares the 4,000-local limit and implements experimental local metering.
• Adds boundary tests for both executors.

File	Description
vm-executor/​src/​lib.rs	Exports the shared local limit.
vm-executor/​src/​compilation_options.rs	Defines the 4,000-local limit.
vm-executor-wasmer/​src/​wasmer_metering.rs	Uses the shared limit.
vm-executor-wasmer/​tests/​locals_test.rs	Tests legacy executor boundaries.
vm-executor-experimental/​Cargo.toml	Upgrades Wasmer to 7.5.
vm-executor-experimental/​src/​middlewares/​we_breakpoints.rs	Adapts middleware lifetimes.
vm-executor-experimental/​src/​middlewares/​we_metering.rs	Adds local limits and metering.
vm-executor-experimental/​src/​middlewares/​we_opcode_control.rs	Adapts middleware lifetimes.
vm-executor-experimental/​src/​middlewares/​we_opcode_trace.rs	Adapts middleware lifetimes.
vm-executor-experimental/​src/​middlewares/​we_protected_globals.rs	Adapts middleware lifetimes.
vm-executor-experimental/​tests/​locals_test.rs	Tests experimental executor boundaries.

🧠 Review effort: Balanced

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