refactor: consolidate release tooling into a single releaser command (#27034)

## What

Consolidates the two separate release programs into a single command at
`scripts/releaser`:

- `scripts/releaser/v1/` — the former interactive releaser (package
`v1`).
- `scripts/releaser/v2/` — the former `scripts/release-action` CI tool
(package `v2`).
- `scripts/releaser/main.go` — new entrypoint. Runs the **v2** tooling
by
  default and the **v1** interactive wizard with `--legacy`.

## CLI shape

Three documented subcommands, each backed by v2 `prepare-release` with
the
release type baked in:

- `releaser rc` — tag a release candidate
- `releaser branch` — cut a new release branch and tag its first RC
- `releaser release` — tag a stable release or patch

The former release-action verbs (`calculate-version`, `prepare-release`,
`generate-notes`, `publish`) are retained as **hidden** top-level
commands with
identical flags and stdout, so `tag-and-release.yaml` migrates with a
path-only
change (`scripts/release-action` -> `scripts/releaser`). `--legacy` runs
the v1
wizard and is mutually exclusive with the subcommands.
`scripts/release.sh` now
launches `releaser --legacy`.

All file moves are rename-detected by git, so the per-file diff is just
the
package declaration.

## Testing

- `go build ./scripts/...`, `go vet ./scripts/releaser/...`, `go test
./scripts/releaser/...`
- `golangci-lint run ./scripts/releaser/...`, `make lint/emdash`,
`shellcheck`, `actionlint`
- Smoke: `releaser --help` shows only rc/branch/release; hidden verbs
still run;
`releaser rc --ref main --dry-run` emits the same JSON contract;
`--legacy rc`
  errors cleanly.

<details>
<summary>Implementation plan</summary>

# Plan: Consolidate release tooling into a single `scripts/releaser`
command

## Goal

Merge the two separate release programs into one binary at
`scripts/releaser`:

- `scripts/releaser/v1/` — the current interactive releaser (package
`v1`).
- `scripts/releaser/v2/` — the current CI `scripts/release-action`
(package `v2`).
- `scripts/releaser/main.go` — new entrypoint (package `main`).
  - Uses v2 by default, v1 with `--legacy`.
- Exposes 3 subcommands: `rc`, `branch` (cut release branch), `release`.

## Design decision (Option A, chosen)

The workflow needs `prepare-release`, `generate-notes`, and `publish`
invokable
separately (a build happens between prepare and publish). The latter two
are
version-driven and type-agnostic, so they do not map cleanly onto
`rc`/`branch`/`release`.

- Visible subcommands `rc`, `branch`, `release` run v2 `prepare-release`
with the
  type baked in and print the same JSON.
- Hidden verbs `calculate-version`, `prepare-release`, `generate-notes`,
  `publish` keep byte-identical flags/stdout, so the workflow change is
  path-only. Lowest risk; honors "3 subcommands" from a UX perspective.

## `--legacy` semantics

- `releaser --legacy` runs the v1 interactive wizard (preserves today's
  behavior; the wizard auto-detects RC vs release from the branch).
- `--legacy` is mutually exclusive with the subcommands (clear error if
  combined), because v1 auto-detects type and cannot cut a branch.

## Work items

1. Create `v1` and `v2` packages via `git mv`, renaming `package main`.
Move the `owner`/`repo` consts into each package. Add `v1.Run(inv,
dryRun)`
   (old wizard `main()` body) and v2 command builders (`CICommands`,
   `TypeCommand`) so internals stay unexported.
2. New `scripts/releaser/main.go`: top-level `releaser` with `--legacy`,
the 3
subcommands, and the hidden compat verbs; delegates to `v1.Run` for
legacy.
3. Update references: `tag-and-release.yaml` (3 command paths + header
comment)
   and `scripts/release.sh` (`--legacy`).
4. Verify: build, vet, test, `go run` smoke tests, fmt, lint.
5. Open a single PR from a feature branch.

## Risks / notes

- stdout contract for rc/branch/release and the hidden verbs must stay
identical
  (workflow parses stdout); logs go to stderr.
- Patch releases from pre-existing `release/X.Y` branches run those
branches'
own (old) workflow + `scripts/release-action`, so they stay
self-consistent.
New releases cut from branches containing this change get the new
workflow +
`scripts/releaser`. No forwarding stub needed since code and workflow
ship
  together.

</details>

---

This PR was created by Coder Agents on behalf of @f0ssel.

.github/workflows/tag-and-release.yaml

@@ -1,9 +1,9 @@
 # Tag and release workflow (GitHub Actions-driven, manual).
 #
 # This is the newer release pipeline driven entirely by the
-# scripts/release-action Go tool. It is triggered manually from the
+# scripts/releaser Go tool. It is triggered manually from the
 # Actions UI. The legacy release.yaml workflow remains in place and is
-# triggered by the scripts/releaser Go tool.
+# triggered by the legacy interactive tool (scripts/releaser --legacy).
 name: Tag and Release
 on:
   workflow_dispatch:
@@ -116,7 +116,7 @@ jobs:
             args+=(--dry-run)
           fi
 
-          output=$(go run ./scripts/release-action prepare-release "${args[@]}")
+          output=$(go run ./scripts/releaser prepare-release "${args[@]}")
           echo "Raw output: $output"
 
           version=$(echo "$output" | jq -r '.version')
@@ -165,7 +165,7 @@ jobs:
           PREV_VERSION: ${{ steps.prepare.outputs.previous_version }}
         run: |
           set -euo pipefail
-          go run ./scripts/release-action generate-notes \
+          go run ./scripts/releaser generate-notes \
             --version "$VERSION" \
             --previous-version "$PREV_VERSION" > /tmp/release_notes.md
 
@@ -643,7 +643,7 @@ jobs:
             stable_flag=(--stable)
           fi
 
-          go run ./scripts/release-action publish \
+          go run ./scripts/releaser publish \
             --version "v${VERSION}" \
             "${stable_flag[@]}" \
             --release-notes-file "$CODER_RELEASE_NOTES_FILE" \