ROX-31479: Change from offset and limit to cursor based paging

[mtodor]

Description

This PR is changing from offset/limit paging to cursor based paging (only for get deployments for CVE) - change for list clusters will be made in a separate PR.

Cursor keeps only offset and limit is defined with constant. This cursor solution allows us to expose limit in the future if it is required.

Validation

• Added unit tests
• Tested with LLM (claude - Sonnet 4.5)

Prompt: Is this CVE affecting me CVE-AAA-BBB?
Response:
Yes, CVE-AAA-BBB is affecting your environment. I found 100+ affected deployments across your two clusters: ..

Prompt: How many deployments and clusters are exactly affected?
Response (after using paging): 
Impact Summary:
  - Total Deployments Affected: 214
  - Total Clusters Affected: 2
  
Prompt: How many platform deployments are affected?
Response (after using paging and filtering properly):
  Total Platform Deployments: 206 out of 214

  This means:
  - 206 platform deployments are affected (infrastructure components)
  - 8 user workload deployments are affected

[codecov-commenter]

❌ 2 Tests Failed:

Tests completed	Failed	Passed	Skipped
225	2	223	0

View the full list of 2 ❄️ flaky test(s)

github.com/stackrox/stackrox-mcp/internal/testutil::

Flake rate in main: 100.00% (Passed 0 times, Failed 2 times)

Stack Traces | 0s run time

Build error

github.com/stackrox/stackrox-mcp/internal/toolsets/mock::

Flake rate in main: 100.00% (Passed 0 times, Failed 2 times)

Stack Traces | 0s run time

Build error

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[janisz]

Maybe add a link to pagination in MCP as for the first look it looks weird that we use base64 to encode int :)