refactor: move source into src/

src/netswitch.ps1 (single file, ~150 lines). CI updated to build from this
path. Added CONTRIBUTING.md describing layout, build, and release flow.

No user-visible behaviour change.

.github/workflows/release.yml

@@ -28,7 +28,7 @@ jobs:
         run: |
           Import-Module ps2exe
           $ver = '${{ steps.ver.outputs.version }}'
-          Invoke-ps2exe -inputFile netswitch.ps1 -outputFile netswitch.exe `
+          Invoke-ps2exe -inputFile src/netswitch.ps1 -outputFile netswitch.exe `
               -title "netswitch" -description "NIC IP/DHCP toggle - made by engelgardt" `
               -company "engelgardt" -version "$ver.0" `
               -requireAdmin

CONTRIBUTING.md

@@ -0,0 +1,62 @@
+# Contributing
+
+> Project layout, build, and release flow. **If you only want to use the tool — read [README](README.md) instead.**
+
+## Repo layout
+
+```
+netswitch/
+├── .github/
+│   ├── workflows/release.yml          ← CI: tag-driven build + GitHub Release
+│   └── ISSUE_TEMPLATE/                ← bug / feature / security routing
+├── src/
+│   └── netswitch.ps1                  ← the whole tool (~150 lines)
+├── CHANGELOG.md                       ← Keep a Changelog format, newest first
+├── CONTRIBUTING.md                    ← this file
+├── LICENSE / README.md / SECURITY.md
+└── .gitignore
+```
+
+## Run from source (no exe)
+
+```
+powershell -ExecutionPolicy Bypass -File src/netswitch.ps1
+```
+
+The script self-elevates through UAC if you launched it without admin.
+
+## Build the portable .exe locally
+
+```
+Install-Module ps2exe -Scope CurrentUser
+Invoke-ps2exe -inputFile src/netswitch.ps1 -outputFile netswitch.exe `
+    -title "netswitch" -description "NIC IP/DHCP toggle - made by engelgardt" `
+    -company "engelgardt" -version "1.0.0.0" `
+    -requireAdmin
+```
+
+## Cut a release
+
+1. Update `src/netswitch.ps1` — bump `$NetswitchVersion` to `X.Y.Z`.
+2. Update `CHANGELOG.md` — move items from `[Unreleased]` into a new `[X.Y.Z]` section with today's date.
+3. Commit: `git commit -am "vX.Y.Z: …"`.
+4. Tag: `git tag vX.Y.Z`.
+5. Push: `git push && git push --tags`.
+
+GitHub Actions picks up the tag, builds the exe via ps2exe, writes the SHA-256, and creates the GitHub Release with the zip attached.
+
+## Where features go
+
+The whole tool is a single PowerShell file with these sections (in order):
+
+1. `$NetswitchVersion` / `$GithubRepo` — top of file.
+2. **Self-elevate** block — UAC if non-admin.
+3. **Banner** — Write-Host title.
+4. **`Test-NetswitchUpdate`** — GitHub /releases/latest poll.
+5. **Adapter filter + picker** — `$skipDescriptionPattern`, `$skipMediaTypes`, `Get-NetAdapter | Where-Object {...}`.
+6. **Mode prompt** — Static / DHCP.
+7. **Static branch** — `netsh interface ipv4 set address ... static ...`.
+8. **DHCP branch** — `netsh interface ipv4 set address ... source=dhcp`.
+9. **Current config display** — `Get-NetIPAddress | Format-Table`.
+
+If a section grows past ~50 lines, factor it into `src/lib/<thing>.ps1` and dot-source it from the main file.