feat(cli): profile ingest runs and split model vs tool time (#249)

* feat(cli): profile ingest runs to find where wall-clock time goes

Add opt-in profiling for `ktx ingest`. Each timed phase, work unit, and
agent loop now records durationMs / step count / token usage in the
trace, and a post-run aggregator rolls them up into a "where did the
time go" report printed to stderr.

Enable per run with KTX_PROFILE_INGEST (1/true -> human table, json ->
raw structured profile) or persistently via `ingest.profile` in
ktx.yaml. The json form emits raw milliseconds, token counts, and a
summary.headline one-line diagnosis so coding agents can parse it
directly; json wins when both env and config request profiling.

- runtime-port: RunLoopMetrics (totalMs, usage, stepCount,
  stepBoundariesMs) plus onMetrics callbacks on text/object generation
- ai-sdk + claude-code runtimes: capture per-loop timing and token usage
- work-unit-executor and stages 3/4: thread metrics into trace events
- ingest-bundle.runner: time worktree / triage / clustering / index /
  reconcile / squash phases and emit the profile in a finally block
  (best-effort; never affects the run outcome)
- ingest-profile: new trace+transcript aggregator with table/json formatters
- config: ingest.profile flag; docs: profiling section in ktx-ingest.mdx

* fix(cli): flush tool-call logs before reading ingest profile

Tool transcripts are appended fire-and-forget so the agent hot path never
blocks on logging. The ingest profiler read them before the writes settled,
so per-work-unit toolMs (and the model-vs-tool split derived from it) could
be incomplete. Track in-flight appends and expose flushToolCallLogs() —
bounded by a timeout so it can never hang — and flush before the profiler
reads the transcript.

packages/cli/src/context/ingest/local-bundle-runtime.ts

@@ -716,6 +716,7 @@ export function createLocalBundleIngestRuntime(
       workUnitMaxConcurrency: options.project.config.ingest.workUnits.maxConcurrency,
       workUnitStepBudget: options.project.config.ingest.workUnits.stepBudget,
       workUnitFailureMode: options.project.config.ingest.workUnits.failureMode,
+      profileIngest: options.project.config.ingest.profile,
       ingestTraceLevel: ingestTraceLevelFromEnv(),
     },
     skillsRegistry: new SkillsRegistryService({ skillsDir, logger }),