chore(github): redesign issue intake forms and routing

Overhaul the bug report form and restructure issue intake for 2.0:

- Bug report: split actual vs expected behavior, add Affected area and
  Specific tool fields for triage, replace the self-defeating required
  "latest version" checkbox with a Version field that accepts a tag,
  release, or commit (always answerable from any install), modernize
  Docker guidance to the Compose stack, add Host OS, and fix the
  previously required image-tag field that source users could not fill.
- Move feature requests to GitHub Discussions: delete the feature_request
  issue form, rename the orphaned discussion form to ideas.yml so it binds
  to the built-in Ideas category, and point config.yml there.
- Add Translation and Documentation issue forms routed to existing labels.
- Remove the roadmap-update discussion form (roadmap is private).
- Reconcile CONTRIBUTING.md, SUPPORT.md, and the published docs
  contributing guide with the new routing.

.github/DISCUSSION_TEMPLATE/roadmap-update.yml

@@ -1,47 +0,0 @@
-title: ""
-labels: []
-body:
-  - type: markdown
-    attributes:
-      value: |
-        Periodic roadmap updates from the maintainers. See the [full roadmap board](https://github.com/orgs/snapotter-hq/projects) for current status.
-
-  - type: textarea
-    id: shipped
-    attributes:
-      label: Shipped
-      description: What landed since the last update?
-    validations:
-      required: false
-
-  - type: textarea
-    id: now
-    attributes:
-      label: Now (actively working on)
-      description: What's currently in progress?
-    validations:
-      required: true
-
-  - type: textarea
-    id: next
-    attributes:
-      label: Next (coming soon)
-      description: What's planned for the near term?
-    validations:
-      required: true
-
-  - type: textarea
-    id: later
-    attributes:
-      label: Later (on the radar)
-      description: What's being considered but not yet scheduled?
-    validations:
-      required: false
-
-  - type: textarea
-    id: community
-    attributes:
-      label: Community highlights
-      description: Shoutouts, top-voted feature requests, notable contributions.
-    validations:
-      required: false