feat(types,core): typed errors for scenario follies

[cds-amal]

This PR was inspired by Stefan Baumgartner Rust talk. It was a fun exercise. Sharing it here in case anyone wants to get it over the line.

Disclaimer: most tests were written by AI.

Error fidelity: before and after

Registering a scenario whose PDA override references a property the values map
does not contain:

Before

{ "jsonrpc": "2.0", "id": 1, "result": { "context": { "slot": 1234 }, "value": null } }

followed, one slot later, by the un-actionable warn above. The override never
applies.

After

{
  "jsonrpc": "2.0", "id": 1,
  "error": {
    "code": -32600,
    "message": "Cannot register scenario 'liquidation drill': override '2f6e0c0d': PDA for program CAMMCzo5YL8w4VFF8KVHrK22GGUsp5VTaW7grrKgrWqK, seed 1: property 'poolId' not found in values"
  }
}

Nothing is scheduled; the caller learns the failing override, the seed position, and the cause in one message. Multiple bad overrides are all reported, joined with "; ", because validation collects every failure before rejecting (one round trip to fix everything, instead of one round trip per mistake).

A sampler of the causes that were previously indistinguishable:

Failure	Message
Garbage pubkey address	invalid account address: 'not-a-pubkey' is not a valid pubkey
Config index too large	PDA for program CAMM..., seed 2: property 'configIndex' value 70000 does not fit in u16
Bad Pyth feed id	PDA for program pyth..., seed 1: 'ef0d8b' is not a 32-byte hex string
Wrong JSON type	PDA for program CAMM..., seed 1: property 'poolId' is bool, expected string or u64
Nested derivation, two levels deep	PDA for program whirl..., seed 0: seed 1 of derived PDA for program whirl...: 'oops' is not a valid pubkey

[greptile-apps]

Greptile Summary

This PR replaces opaque scenario address-resolution failures with typed, contextual errors and validates enabled override addresses before scheduling.

• Adds structured seed, address, and override error types.
• Returns aggregated JSON-RPC errors for invalid scenario overrides.
• Refactors scheduled override application to report typed failures.
• Validates embedded scenario templates and updates documentation and tests.

Confidence Score: 5/5

The PR appears safe to merge, with no concrete changed-code defect identified.

The new typed-error paths consistently propagate address-resolution failures through template loading, scenario registration, and scheduled override handling, and repository call sites have been updated for the fallible APIs.

Important Files Changed

Filename	Overview
crates/types/src/scenarios.rs	Introduces typed seed/address/application errors, fallible PDA resolution and template conversion, plus comprehensive unit coverage.
crates/core/src/surfnet/svm.rs	Validates enabled override addresses before scheduling and extracts typed override application while retaining existing materialization semantics.
crates/core/src/error.rs	Maps scenario failures into aggregated invalid-request JSON-RPC errors.
crates/core/src/scenarios/registry.rs	Handles fallible template conversion during built-in registry initialization and updates resolution tests.
crates/core/src/rpc/surfnet_cheatcodes.rs	Documents registration-time validation behavior without changing the RPC method shape.
crates/mcp/src/surfpool/mod.rs	Updates MCP guidance so clients can correct address-resolution failures and retry.
crates/core/src/scenarios/README.md	Documents up-front enabled-override address validation and aggregated failure reporting.

_{Reviews (1): Last reviewed commit: "cargo: fmt" | Re-trigger Greptile}