fix: dont propogate import rows

[luke-lombardi]

Summary by cubic

Stop propagating imported rows to other sheets. Removed the background goroutine and deleted propagateImportRows, so ImportData now writes only to the source sheet to prevent unexpected writes and long-running syncs.

^{Written for commit 3fb8098. Summary will update on new commits.}

[github-actions]

✅ Integration Tests PASSED

Gateway: https://api.airstore.ai
Query path: /sources/gmail/unread-emails
Timestamp: 2026-04-07T19:09:30Z

I/O Smoke Tests

Test	Status	Latency	Bytes
list_sources	PASS	115ms	-
list_gmail	PASS	278ms	-
list_query_path	PASS	925ms	-
read_file	PASS	368ms	1,724
stat_file	PASS	117ms	69,626

Compression A/B Tests

Metric	Value
Files tested	8
Total raw bytes	73,033
Total strip bytes	46,330
Total raw tokens	41,729
Total strip tokens	27,530
Tokens saved	14,199
Byte reduction	36%
Token reduction	34%
Min threshold	10%
Cache consistent	Yes

Per-file results

File	Raw B	Strip B	Raw Tok	Strip Tok	Tok Saved	Red%	Raw ms	Strip ms
2024-10-15_Harris-Walz_Organizing_Tea...	2,337	2,305	976	967	9	1%	244ms	123ms
2024-10-15_Stephen_King_via_KamalaHar...	2,904	2,866	1,116	1,103	13	1%	1081ms	126ms
2025-07-17_KAYAK_How_to_have_everythi...	1,724	1,670	1,220	1,204	16	3%	171ms	121ms
2025-07-17_Alamo_Drafthouse_Cinema_Th...	19,047	18,224	12,228	11,704	524	4%	257ms	141ms
2025-07-17_Alamo_Drafthouse_Cinema_Th...	18,978	18,155	12,105	11,578	527	4%	268ms	138ms
2024-10-15_Knut_at_Sanity_Join_us_tom...	1,272	726	504	209	295	42%	452ms	122ms
2025-07-17_Lindsay_Stanley_TODAY_Conf...	1,876	1,049	657	268	389	44%	226ms	121ms
2025-07-17_NORDSTROM_RACK_FLASH_Travi...	24,895	1,335	12,923	497	12,426	94%	257ms	140ms

Charts

Overall Compression	Raw vs Compressed Bytes	Token Comparison
Reduction by File	Read Latency	I/O Latency