refactor(agent-service): redesign sync-execution result and error model

[bobbai00]

What changes were proposed in this PR?

Stacked on apache#5751 (foundation). This is the second of the split: it carries the sync-execution result/error model redesign (no overlap with the foundation PR — types/execution.ts is untouched there).

• Replace the flat OperatorInfo with OperatorExecutionSummary (orthogonal sub-summaries: state, errorMessages, resultSummary?, consoleLogsSummary?); rename SyncExecutionResult → WorkflowExecutionSummary.
• resultSummary.sampleTuples is now SampleRow[] ({ rowIndex, tuple }) instead of JSON rows with an embedded __row_index__; drop the table-shape types (the agent derives input-port shapes from the DAG).
• Reuse the engine's WorkflowFatalError for per-operator errors (the same type the compiling service returns), replacing the bespoke OperatorError so compile and execution errors share one wire shape.
• errorMessages / errors are non-optional (empty = none); drop compilationErrors; collapse the console-message types and derive warnings from WARNING:-titled messages.
• The WS operatorResults payload carries the canonical OperatorExecutionSummary; the frontend maps it to its flat display type.

Touches the Scala producer (SyncExecutionResource), the agent-service consumers (result-formatting, workflow-execution-tools, workflow-result-state, server), and the frontend WS mapping. Representation/type-level; behavior preserved (input-port shape lines are now derived rather than explicitly rendered).

Any related issues, documentation, discussions?

Part of apache#5747. Depends on apache#5751 — review/merge that first. (This is a draft stacked on the foundation branch; it will be retargeted to main once apache#5751 lands.)

How was this PR tested?

• bunx tsc --noEmit, bun test (121 pass / 0 fail), prettier --check in agent-service; sbt WorkflowExecutionService/compile for amber.
• End-to-end on the full local stack with a Claude Haiku 4.5 agent: it built and executed a CSV workflow; /operator-results returned the new shape — resultSummary.sampleTuples: [{ rowIndex, tuple }], errorMessages: [] — and the agent rendered the rows correctly.

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[bobbai00]

Superseded by apache#5927 (opened against apache:main).

[github-actions]

⚠️ Benchmark changes need a look

🟢 2 better · 🔴 5 worse · ⚪ 8 noise (<±5%) · 0 without baseline

Compared against main 2bae592 benchmarked on this same runner, so the delta is largely free of cross-runner hardware noise. The "7d avg" column still reflects the gh-pages dashboard. Treat <±5% as noise unless repeated.

Dashboard · Run

	config	throughput	MB/s	latency	max Δ latest / 7d
🔴	bs=10 sw=10 sl=64	385	0.235	25,109/42,262/42,262 us	🔴 +25.4% / ⚪ within ±5%
🟢	bs=100 sw=10 sl=64	835	0.51	118,572/140,438/140,438 us	🟢 -7.7% / ⚪ within ±5%
⚪	bs=1000 sw=10 sl=64	949	0.58	1,057,487/1,096,278/1,096,278 us	⚪ within ±5% / ⚪ within ±5%

Baseline details

Latest main 2bae592 from same runner

config	metric	PR	latest main	7d avg	Δ latest	Δ 7d
bs=10 sw=10 sl=64	throughput	385 tuples/sec	416 tuples/sec	n/a	-7.5%	n/a
bs=10 sw=10 sl=64	MB/s	0.235 MB/s	0.254 MB/s	n/a	-7.5%	n/a
bs=10 sw=10 sl=64	p50	25,109 us	23,847 us	n/a	+5.3%	n/a
bs=10 sw=10 sl=64	p95	42,262 us	33,714 us	n/a	+25.4%	n/a
bs=10 sw=10 sl=64	p99	42,262 us	33,714 us	n/a	+25.4%	n/a
bs=100 sw=10 sl=64	throughput	835 tuples/sec	849 tuples/sec	n/a	-1.6%	n/a
bs=100 sw=10 sl=64	MB/s	0.51 MB/s	0.518 MB/s	n/a	-1.5%	n/a
bs=100 sw=10 sl=64	p50	118,572 us	115,733 us	n/a	+2.5%	n/a
bs=100 sw=10 sl=64	p95	140,438 us	152,184 us	n/a	-7.7%	n/a
bs=100 sw=10 sl=64	p99	140,438 us	152,184 us	n/a	-7.7%	n/a
bs=1000 sw=10 sl=64	throughput	949 tuples/sec	948 tuples/sec	n/a	+0.1%	n/a
bs=1000 sw=10 sl=64	MB/s	0.58 MB/s	0.579 MB/s	n/a	+0.2%	n/a
bs=1000 sw=10 sl=64	p50	1,057,487 us	1,053,859 us	n/a	+0.3%	n/a
bs=1000 sw=10 sl=64	p95	1,096,278 us	1,088,189 us	n/a	+0.7%	n/a
bs=1000 sw=10 sl=64	p99	1,096,278 us	1,088,189 us	n/a	+0.7%	n/a

Raw CSV

config_idx,batch_size,schema_width,string_len,num_batches,total_ms,total_tuples,total_bytes,tuples_per_sec,mb_per_sec,lat_p50_us,lat_p95_us,lat_p99_us
0,10,10,64,20,519.41,200,128000,385,0.235,25108.90,42261.57,42261.57
1,100,10,64,20,2395.00,2000,1280000,835,0.510,118572.45,140438.42,140438.42
2,1000,10,64,20,21064.07,20000,12800000,949,0.580,1057487.22,1096277.97,1096277.97