build: speed up debug compile loop

- Drop libsqlite3-sys 'bundled' on Linux/macOS so the SQLite C source
  isn't recompiled every clean build; Windows keeps 'bundled' via a
  cfg(windows) target override.
- Switch opentelemetry-otlp from grpc-tonic to http-proto + reqwest-client.
  Removes the tonic + h2 + hyper-h2 stack from the build graph; reqwest
  was already a dependency. Updates otel.rs to call .with_http().
- Add [profile.dev] debug = "line-tables-only" to shrink linker work
  while keeping panics/backtraces useful.
- Add .cargo/config.toml selecting mold via gcc on x86_64-linux-gnu.
  Requires `apt install mold`. Other platforms use the default linker.
- cargo update: lockfile-only refresh of all minor/patch bumps within
  existing version constraints.

Cold debug build: ~1m 37s; touch-one-file rebuild: ~5s on Linux.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.cargo/config.toml

@@ -0,0 +1,3 @@
+[target.x86_64-unknown-linux-gnu]
+linker = "/usr/bin/gcc"
+rustflags = ["-C", "link-arg=-fuse-ld=mold"]

Cargo.toml

@@ -9,6 +9,9 @@ edition = "2024"
 [profile.release]
 lto = "thin"
 
+[profile.dev]
+debug = "line-tables-only"
+
 [dependencies]
 actix = "0.13.1"
 actix-web = "4"
@@ -23,7 +26,7 @@ jsonwebtoken = "9.3.0"
 serde = "1"
 serde_json = "1"
 diesel = { version = "2.2.10", features = ["sqlite"] }
-libsqlite3-sys = { version = "0.35", features = ["bundled"] }
+libsqlite3-sys = "0.35"
 diesel_migrations = "2.2.0"
 chrono = "0.4"
 clap = { version = "4.5", features = ["derive"] }
@@ -41,9 +44,9 @@ prometheus = "0.13"
 lazy_static = "1.5"
 anyhow = "1.0"
 rand = "0.8.5"
-opentelemetry = { version = "0.31.0", features = ["default", "metrics", "tracing"] }
-opentelemetry_sdk = { version = "0.31.0", features = ["default", "rt-tokio-current-thread", "metrics"] }
-opentelemetry-otlp = { version = "0.31.0", features = ["default", "metrics", "tracing", "grpc-tonic"] }
+opentelemetry = { version = "0.31.0", features = ["metrics", "trace"] }
+opentelemetry_sdk = { version = "0.31.0", features = ["rt-tokio-current-thread", "metrics", "logs"] }
+opentelemetry-otlp = { version = "0.31.0", default-features = false, features = ["trace", "metrics", "logs", "http-proto", "reqwest-client"] }
 opentelemetry-stdout = "0.31.0"
 opentelemetry-appender-log = "0.31.0"
 tempfile = "3.20.0"
@@ -63,3 +66,8 @@ image_hasher = "3.0"
 bk-tree = "0.5"
 async-trait = "0.1"
 indicatif = "0.17"
+
+# Windows lacks system sqlite3, so re-enable the bundled C build there.
+# Linux/macOS use the system library (faster builds, smaller binary).
+[target.'cfg(windows)'.dependencies]
+libsqlite3-sys = { version = "0.35", features = ["bundled"] }

src/otel.rs

@@ -24,7 +24,7 @@ pub fn init_tracing() {
         .build();
 
     let span_exporter = opentelemetry_otlp::SpanExporter::builder()
-        .with_tonic()
+        .with_http()
         .with_endpoint(std::env::var("OTLP_OTLS_ENDPOINT").unwrap())
         .build()
         .unwrap();
@@ -40,7 +40,7 @@ pub fn init_tracing() {
 #[allow(dead_code)]
 pub fn init_logs() {
     let otlp_exporter = opentelemetry_otlp::LogExporter::builder()
-        .with_tonic()
+        .with_http()
         .with_endpoint(std::env::var("OTLP_OTLS_ENDPOINT").unwrap())
         .build()
         .unwrap();