feat: implement endpoint to support fetching workspace pod log

[YoyinZyc]

Implement the batch log API proposed in #886 (comment)
closes: #887
related: #886

Behavior

A new one-shot endpoint returning a workspace pods container(including the initContainer like istio) logs as a plain text.

Query params: container(defaults to first/primary container); tail(default to 1000); previous (default to false); sinceTime(default to none)

API

GET /api/v1/workspaces/{namespace}/{name}/podtemplate/logs/batch
      ?container=<name>    # optional, defaults to the first (primary) container
      &tail=<int>          # optional, default 1000
      &previous=<bool>     # optional, default false (previous terminated instance)
      &sinceTime=<string> #optional, default to none

Response

2026-07-23T18:37:19.502427795Z 2026-07-23T18:37:19.502162Z	info	xdsproxy	connected to delta upstream XDS server: istiod.istio-system.svc:15012	id=96
2026-07-23T19:07:20.316168674Z 2026-07-23T19:07:20.315975Z	info	xdsproxy	connected to delta upstream XDS server: istiod.istio-system.svc:15012	id=97
2026-07-23T19:36:29.611434886Z 2026-07-23T19:36:29.611255Z	info	xdsproxy	connected to delta upstream XDS server: istiod.istio-system.svc:15012	id=98
2026-07-23T20:04:05.870345556Z 2026-07-23T20:04:05.870108Z	info	xdsproxy	connected to delta upstream XDS server: istiod.istio-system.svc:15012	id=99
2026-07-23T20:32:49.598960074Z 2026-07-23T20:32:49.598795Z	info	xdsproxy	connected to delta upstream XDS server: istiod.istio-system.svc:15012	id=100
2026-07-23T21:01:53.168136917Z 2026-07-23T21:01:53.167896Z	info	xdsproxy	connected to delta upstream XDS server: istiod.istio-sy

Unit tests

internal/repositories/logs/repo_test.go
workspace_logs_handler_test.go

Tested Manually

BASE_URL=https://localhost:8443/workspaces/api/v1/workspaces/default/jupyterlab-workspace/podtemplate/logs/batch

Positive

Path	HTTP Code	Result
empty	200	default the main container with tail set to 1000 and previous=false
tail=15	200	15 line of log
container=main	200	return log for main container
container=istio-proxy	200	return log for istio proxy
sinceTime=2026-07-23T18:30:00Z	200	return main log since that time
container=istio-proxy&sinceTime=2026-07-23T18:30:00Z	200	return istio proxy log since that time

Negative

Path	HTTP Code	Error Msg
previous=true(never restarted)	409	no logs found for the previous container instance
container=	400	container not found in pod
tail= / tail=0 / previous=maybe / sinceTime=	422	field validation error
non-existent workspace	404	workspace not found
non-running container(in waiting state)	409	container has not started yet (note: this one is hard to test manually, mostly rely on unit test)

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[christian-heusel]

@YoyinZyc FYI I have added a compression middleware to the backend in parallel which should help quite a bit for the log endpoint 🤗 #1269