fix: delete broken task-dump examples and fix CI to catch example failures

The `task_dump` module was removed but 4 examples (long_sleep,
completing_task, cancelled_task, debug_timing) and 1 bench
(poll_overhead) that depended on it were left behind. These compiled
fine in the default CI because:

1. `cargo build` didn't use `--all-features` or `--all-targets`, so
   feature-gated examples were never compiled
2. `cargo clippy` didn't use `--all-targets` or `--all-features`, so
   examples and feature-gated code were not linted

Only the nightly stress test (which uses `--all-features`) caught the
breakage.

Changes:
- Delete 4 broken task-dump examples and 1 broken bench
- Remove the `task-dump` feature from Cargo.toml and README
- Build action: `cargo build` → `cargo build --all-targets --all-features`
- Build action: `cargo test` → `cargo test --all-features`
- Clippy: `cargo clippy --workspace` → `cargo clippy --all-targets --all-features`

Author: rcoh

.github/actions/rust-build/action.yml

@@ -20,7 +20,7 @@ runs:
               if [ "${{ inputs.toolchain }}" != stable ]; then
                   rm -fv Cargo.lock
               fi
-              cargo build
+              cargo build --all-targets --all-features
         - name: Enable perf_event_open and kallsyms for tests
           shell: bash
           run: |
@@ -33,4 +33,4 @@ runs:
           run: |
               # Raise locked-memory limit for large perf ring buffers
               sudo prlimit --pid $$ --memlock=unlimited:unlimited
-              cargo test
+              cargo test --all-features

.github/workflows/format.yml

@@ -25,4 +25,4 @@ jobs:
         shell: bash
         env:
           RUSTFLAGS: "--cfg tokio_unstable"
-        run: cargo clippy --workspace -- -D warnings
+        run: cargo clippy --all-targets --all-features -- -D warnings

Cargo.lock

@@ -42,7 +42,6 @@ metrique = { version = "0.1.23", features = ["local-format"] }
 [features]
 analysis = []
 cpu-profiling = ["dep:dial9-perf-self-profile"]
-task-dump = ["tokio/taskdump"]
 worker-s3 = ["dep:aws-sdk-s3-transfer-manager", "dep:aws-sdk-s3", "dep:aws-config", "dep:time"]
 
 [dev-dependencies]
@@ -67,31 +66,10 @@ uuid = { version = "1", features = ["v4"] }
 dial9-tokio-telemetry = { path = ".", features = ["cpu-profiling", "worker-s3", "analysis"] }
 nix = { version = "0.29", features = ["process"] }
 
-[[bench]]
-name = "poll_overhead"
-harness = false
-required-features = ["task-dump"]
-
 [[bench]]
 name = "overhead_bench"
 harness = false
 
-[[example]]
-name = "long_sleep"
-required-features = ["task-dump"]
-
-[[example]]
-name = "completing_task"
-required-features = ["task-dump"]
-
-[[example]]
-name = "cancelled_task"
-required-features = ["task-dump"]
-
-[[example]]
-name = "debug_timing"
-required-features = ["task-dump"]
-
 [[example]]
 name = "blocking_sleep"
 required-features = ["cpu-profiling"]

dial9-tokio-telemetry/Cargo.toml

@@ -221,7 +221,6 @@ See [TRACE_ANALYSIS_GUIDE.md](/dial9-tokio-telemetry/TRACE_ANALYSIS_GUIDE.md) fo
 ## Features
 
 - **`cpu-profiling`** — Linux only. Enables `perf_event_open`-based CPU sampling and scheduler event capture via `dial9-perf-self-profile`.
-- **`task-dump`** — Enables Tokio's `taskdump` feature for async stack traces. Required for the `long_sleep`, `completing_task`, `cancelled_task`, and `debug_timing` examples.
 - **`worker-s3`** — Enables S3 upload support. Adds `aws-sdk-s3`, `aws-sdk-s3-transfer-manager`, `aws-config`, and `flate2`.
 
 ## S3 upload