fix: use service name const instead of string literal in generated clients

[paikend]

Summary

Addresses #9 — the codegen emits a *_SERVICE_NAME const for each service, but generated client methods were repeating the fully-qualified name as a string literal instead of referencing the const.

• Generated client methods (call_unary, call_server_stream, call_client_stream, call_bidi_stream) were using the fully-qualified service name as a string literal, even though the codegen already emits a *_SERVICE_NAME const at the top of each generated file.
• The server-side router already references the const (3 sites per service in the ELIZA example), but client call sites did not — this inconsistency meant renaming a service required updating both the const definition and every client call site.
• The dispatcher's strip_prefix("service.name/") calls use a trailing-slash form and stay as-is (as noted in the issue).

Problem (from #9)

// Codegen emits this const:
pub const ELIZA_SERVICE_SERVICE_NAME: &str = "connectrpc.eliza.v1.ElizaService";

// But generated client methods repeated the literal:
call_unary(
    &self.transport, &self.config,
    "connectrpc.eliza.v1.ElizaService",  // ← should be ELIZA_SERVICE_SERVICE_NAME
    "Say",
    request, options,
).await

Fix

Changed generate_client_method to accept the const Ident and emit it at all four call sites:

// AFTER:
call_unary(
    &self.transport, &self.config,
    ELIZA_SERVICE_SERVICE_NAME,  // ← references the const
    "Say",
    request, options,
).await

Changes

• connectrpc-codegen/src/codegen.rs:
  • Added Ident to proc_macro2 import
  • generate_client_method now takes service_name_const: &Ident + full_service_name: &str (kept for doc strings)
  • All 4 call sites (call_unary, call_server_stream, call_client_stream, call_bidi_stream) emit the const ident instead of the string literal

Type safety

• call_unary etc. expect service: &str
• The const is pub const *_SERVICE_NAME: &str = "..." → coerces to &str ✓

Test plan

• cargo check --package connectrpc-codegen — compiles cleanly
• cargo test --package connectrpc-codegen — 10 tests passed
• Regenerate examples with buf generate to verify generated output uses the const (requires buf CLI + protoc)

Closes #9

🤖 Generated with Claude Code

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[paikend]

I have read the CLA Document and I hereby sign the CLA

[iainmcgin]

Thanks for the fix! I'll push the formatting fix onto your branch and merge.

[iainmcgin]

LGTM. Service-name const reference brings client emission into structural symmetry with the server-side dispatcher (which already uses the same const at 4 sites). Pushed an rustfmt fix to wrap the call.