Update Go toolchain to 1.26

[Copilot]

Upgrades Go toolchain from 1.24 to 1.26.0 (latest stable release).

Changes

• go.mod: Updated go directive to 1.26
• .gitignore: Added gdk binary exclusion

GitHub Actions workflows already use go-version-file: 'go.mod' and will automatically pick up the new version.

Original prompt

Repository: rizalgowandy/gdk

Goal: Update the Go toolchain version used by this repository to the latest stable Go release and ensure the project builds/tests successfully with it.

Tasks:

1. Identify all places where the Go version is pinned or referenced (e.g., go.mod go directive and/or toolchain, GitHub Actions workflows, Dockerfiles, Makefiles, build scripts, CI configs, devcontainer files, README/docs).
2. Update those references to the latest stable Go version.
   • Update go.mod appropriately (including go directive; and toolchain directive if present/appropriate).
   • Update CI (e.g., actions/setup-go) to use the same version.
3. Run/update tests and any linters as needed; fix any compilation or tooling issues caused by the version bump.
4. If dependency or module tidying is required due to the version change, run go mod tidy and commit resulting changes.
5. Ensure documentation reflects the new required Go version.

Acceptance criteria:

• CI configuration uses the new Go version.
• go.mod reflects the new Go version.
• Repository builds and tests pass on the new Go version.
• Any required accompanying changes (mod tidy, tooling updates) are included.

Notes:

• Use the latest stable Go release available at the time of implementation.
• Keep changes minimal and focused on the Go version upgrade and necessary follow-up fixes.

This pull request was created from Copilot chat.

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[github-actions]

Code Metrics Report

	main (2d50b5c)	#51 (d12ea05)	+/-
Coverage	29.5%	29.5%	0.0%
Code to Test Ratio	1:0.7	1:0.7	0.0
Test Execution Time	44s	43s	-1s

Details

  |                     | main (2d50b5c) | #51 (d12ea05) | +/-  |
  |---------------------|----------------|---------------|------|
  | Coverage            |          29.5% |         29.5% | 0.0% |
  |   Files             |            113 |           113 |    0 |
  |   Lines             |           2580 |          2580 |    0 |
  |   Covered           |            762 |           762 |    0 |
  | Code to Test Ratio  |          1:0.7 |         1:0.7 |  0.0 |
  |   Code              |           6745 |          6745 |    0 |
  |   Test              |           5113 |          5113 |    0 |
+ | Test Execution Time |            44s |           43s |  -1s |

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Reported by octocov