chore: redirect e2e output files to test-output/, tighten .gitignore

[jacalata]

Summary

• E2e tests were writing .twbx, .tdsx, .csv, .pdf, .png files into the repo root
• Added OUTPUT_DIR = "test-output/" constant in online_tests.py; all output paths now write there
• Added test-output/ to .gitignore along with explicit *.csv, *.twbx, *.tdsx patterns and *.log.* for numbered log rotation files

Test plan

• Run e2e tests and verify output files appear in test-output/ not repo root

🤖 Generated with Claude Code

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
tabcmd
__main__.py	10	10	10	0%
_version.py	11	11	11	0%
tabcmd.py	15	15	15	0%
version.py	9	5	5	44%
tabcmd/commands
commands.py	10	10	10	0%
constants.py	77	18	18	77%
server.py	135	18	18	87%
tabcmd/commands/auth
session.py	381	46	46	88%
tabcmd/commands/datasources_and_workbooks
datasources_and_workbooks_command.py	157	18	18	89%
datasources_workbooks_views_url_parser.py	142	5	5	96%
delete_command.py	60	16	16	73%
export_command.py	120	25	25	79%
get_url_command.py	127	47	47	63%
publish_command.py	123	28	28	77%
runschedule_command.py	21	7	7	67%
tabcmd/commands/extracts
create_extracts_command.py	42	8	8	81%
decrypt_extracts_command.py	27	2	2	93%
delete_extracts_command.py	37	6	6	84%
encrypt_extracts_command.py	27	2	2	93%
extracts.py	20	2	2	90%
reencrypt_extracts_command.py	27	2	2	93%
refresh_extracts_command.py	48	10	10	79%
tabcmd/commands/group
create_group_command.py	29	5	5	83%
delete_group_command.py	27	2	2	93%
tabcmd/commands/project
create_project_command.py	46	8	8	83%
delete_project_command.py	35	4	4	89%
publish_samples_command.py	30	4	4	87%
tabcmd/commands/site
create_site_command.py	34	5	5	85%
delete_site_command.py	27	2	2	93%
edit_site_command.py	38	2	2	95%
list_command.py	77	12	12	84%
list_sites_command.py	29	2	2	93%
tabcmd/commands/user
add_users_command.py	29	5	5	83%
create_site_users.py	58	11	11	81%
create_users_command.py	60	10	10	83%
delete_site_users_command.py	43	5	5	88%
user_data.py	221	31	31	86%
tabcmd/execution
_version.py	2	2	2	0%
global_options.py	125	8	8	94%
localize.py	66	11	11	83%
logger_config.py	52	6	6	88%
tabcmd_controller.py	42	7	7	83%
TOTAL	2850	453	84%