Refactor plan: reuse injection logic cleanly

1. Model

• Add enum InjectionScope { Outer, Inner }.
• Extend the injected‑parameter resolver to accept { scope, callSiteContext? }.

2. Binding

• Map names to sources per scope:
• Inner: __instance, inner arg names, __result, __args?.
• Outer: existing mapping. Trigger via o_ prefix.
• Outer locals: _var<index>.
• Synthetic: _var<name> declared once per outer method and reused.

3. Emission

• Do not fork the emitter.
• Add small hooks:
  • Provide “value loader” and “address loader” delegates per source so the existing emitter can push either ldloc or ldloca or outer ldarg[a] etc.
  • For inner __result, bypass outer result plumbing and use the call‑site local.

4. Minimal changes by file

• PatchModels.cs: add inner patch types and InnerMethod.
• PatchClassProcessor.cs: detect [HarmonyInfixPrefix/Postfix], parse [HarmonyInfixTarget], attach InnerMethod.
• PatchInfo.cs: store inner prefix/postfix arrays. Remove patch support covers them too.
• PatchFunctions.cs: filter/sort inner patches per call occurrence.
• MethodCreatorTools.cs: extend parameter resolver with InjectionScope and _var* handling.
• MethodCreator.cs: implement AddInfixes(...) pass that replaces calls per algorithm.
• Infix.cs: optional thin helpers for per‑site context.

5. No duplication

• The only special‑case logic lives in:
  • call‑site stack capture,
  • inner __result handling,
  • absorption of call‑only prefixes.