feat(detector): implement Mise detection

[dipto0321]

Summary

Add the Mise (https://mise.jdx.dev) detector — the 5th of 8 Node.js version managers in the Phase 1 detection rollout.

Unlike ASDF, Mise requires the CLI to be authoritative: we look at mise ls --installed --json node rather than walking $MISE_DATA_DIR/installs/node/, because the CLI handles active-vs-installed, symlinks, and config-resolved versions in one shot.

Changes

• internal/detector/mise.go (full implementation):
  • Detect(): platform.LookupManagerBinary("mise") != ""
  • Version(): mise --version, first whitespace-separated token with optional v prefix stripped (CalVer like 2026.6.15)
  • ListInstalled(): mise ls --installed --json node, JSON-decoded into a struct that mirrors upstream JSONToolVersion (defensively skipped fields: requested_version, source, sources, symlinked_to, installed, active)
  • Mutation methods return ErrMiseNotImplemented sentinel (matches the ASDF pattern from PR feat(detector): implement ASDF detection #4)
• internal/detector/mise_test.go (27 mocked tests):
  • parseMiseVersion: CalVer output, v prefix, leading/trailing whitespace, empty, whitespace-only
  • parseMiseInstalled: real JSON output, unsorted input → sorted ascending, empty array, empty stdout, skips installed:false, skips empty version, skips non-semver versions, malformed JSON hard error, ignores unknown future fields
  • Method tests: Name, Version (success/V-prefixed/runShell error/parsing error), ListInstalled (success/empty array/empty stdout/runShell error/JSON parse error)
  • Detect: PATH-without-binary, PATH-with-binary on the stub (Windows-safe via mise.exe)
  • MutationMethods_NotImplemented sentinel test

Design notes

• The miseToolVersion struct uses omitempty on optional fields so future upstream additions never break parsing (covered by IgnoresExtraFields test).
• We filter on Installed: true after JSON decode as a defense-in-depth check, since we pass --installed upstream — if Mise ever ignores that flag (bug or design change), we still return a clean list.
• CalVer (2026.6.15) is intentionally NOT validated as semver in parseMiseVersion — matching ASDF's policy of returning the raw token for the caller to handle.

Test plan

• go test ./... — all packages green
• go vet ./... — clean
• gofmt -l — clean
• CI matrix: lint (ubuntu), test on ubuntu/macos/windows, build on 5 platforms — pending

[cocogitto-bot]

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