chore: bump Go to 1.26, refresh deps, and add setup task

[rizalgowandy]

Summary

• bump module Go version from 1.24.9 to 1.26
• bump github.com/rizalgowandy/gdk from v1.2.0 to v1.3.0
• refresh dependency versions in go.mod/go.sum
• add task setup as a developer bootstrap entrypoint (delegates to existing tools task)

Verification

• GOTOOLCHAIN=auto GOFLAGS=-mod=mod go generate ./...
• GOTOOLCHAIN=auto GOFLAGS=-mod=mod go test ./...
• GOTOOLCHAIN=auto GOFLAGS=-mod=mod go build ./...
• GOTOOLCHAIN=auto GOFLAGS=-mod=mod golangci-lint run ./...
• task --dry setup

[github-actions]

Code Metrics Report

	main (4addbb6)	#40 (db1275e)	+/-
Coverage	38.8%	38.8%	0.0%
Code to Test Ratio	1:0.7	1:0.7	0.0
Test Execution Time	25s	11s	-14s

Details

  |                     | main (4addbb6) | #40 (db1275e) | +/-  |
  |---------------------|----------------|---------------|------|
  | Coverage            |          38.8% |         38.8% | 0.0% |
  |   Files             |             25 |            25 |    0 |
  |   Lines             |            559 |           559 |    0 |
  |   Covered           |            217 |           217 |    0 |
  | Code to Test Ratio  |          1:0.7 |         1:0.7 |  0.0 |
  |   Code              |           2104 |          2104 |    0 |
  |   Test              |           1506 |          1506 |    0 |
+ | Test Execution Time |            25s |           11s | -14s |

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Reported by octocov