fix email formatting for gmail client

[luke-lombardi]

Summary by cubic

Send HTML emails from the Gmail client so messages render correctly in Gmail (paragraphs, lists, and links). Also improves relevance when pulling view data and prevents cross-sheet writes to unrelated sheets.

• Bug Fixes

  • Gmail: set Content-Type: text/html and convert plain text to simple HTML (paragraphs, bullets/numbered lists, auto-linked URLs, mobile viewport). Tests added in pkg/tools/clients/gmail_test.go.

• New Features

  • Context enrichment: FetchViewRows now accepts a queryHint and uses vector search when available; otherwise pages the first table only. Callers pass the composed message as the hint for better relevance.
  • View data context: add per-sheet character budgets to avoid overlong contexts.
  • Embeddings: add BulkUpdateEmbeddings to persist embeddings without clobbering cells; used by async row embedding.
  • View sync: filter cross-sheet targets by minimum column overlap to avoid inserting into unrelated sheets; make tool-write sync run async to reduce latency.

^{Written for commit 9cbb912. Summary will update on new commits.}

[github-actions]

✅ Integration Tests PASSED

Gateway: https://api.airstore.ai
Query path: /sources/gmail/unread-emails
Timestamp: 2026-04-07T22:18:31Z

I/O Smoke Tests

Test	Status	Latency	Bytes
list_sources	PASS	372ms	-
list_gmail	PASS	410ms	-
list_query_path	PASS	606ms	-
read_file	PASS	419ms	1,724
stat_file	PASS	294ms	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%	442ms	299ms
2024-10-15_Stephen_King_via_KamalaHar...	2,904	2,866	1,116	1,103	13	1%	402ms	304ms
2025-07-17_KAYAK_How_to_have_everythi...	1,724	1,670	1,220	1,204	16	3%	296ms	300ms
2025-07-17_Alamo_Drafthouse_Cinema_Th...	19,047	18,224	12,228	11,704	524	4%	520ms	370ms
2025-07-17_Alamo_Drafthouse_Cinema_Th...	18,978	18,155	12,105	11,578	527	4%	502ms	396ms
2024-10-15_Knut_at_Sanity_Join_us_tom...	1,272	726	504	209	295	42%	423ms	298ms
2025-07-17_Lindsay_Stanley_TODAY_Conf...	1,876	1,049	657	268	389	44%	413ms	294ms
2025-07-17_NORDSTROM_RACK_FLASH_Travi...	24,895	1,335	12,923	497	12,426	94%	527ms	306ms

Charts

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