feat!: unify mosaic CLI — native launcher, no bin/ directory

BREAKING CHANGE: ~/.config/mosaic/bin/ is removed entirely.
The mosaic npm CLI is now the only executable.

## What changed

- **bin/ → deleted**: All scripts moved to tools/_scripts/ (internal)
- **mosaic-launch → deleted**: Launcher logic is native TypeScript
  in packages/cli/src/commands/launch.ts
- **mosaic.ps1 → deleted**: PowerShell launcher removed
- **Framework install.sh**: Complete rewrite with migration system
- **Version tracking**: .framework-version file (schema v2)
- **Migration v1→v2**: Auto-removes bin/, cleans old PATH entries
  from shell profiles

## Native TypeScript launcher (commands/launch.ts)

All runtime launch logic ported from bash:
- Runtime prompt builder (AGENTS.md + RUNTIME.md + USER.md + TOOLS.md)
- Mission context injection (reads .mosaic/orchestrator/mission.json)
- PRD status injection (scans docs/PRD.md)
- Pre-flight checks (MOSAIC_HOME, AGENTS.md, SOUL.md, runtime binary)
- Session lock management with signal cleanup
- Per-runtime launch: Claude, Codex, OpenCode, Pi
- Yolo mode flags per runtime
- Pi skill discovery + extension loading
- Framework management (init, doctor, sync, bootstrap) delegates
  to tools/_scripts/ bash implementations

## Installer

- tools/install.sh: detects framework by .framework-version or AGENTS.md
- Framework install.sh: migration system with schema versioning
- Forward-compatible: add migrations as numbered blocks
- No PATH manipulation for framework (npm bin is the only PATH entry)

packages/mosaic/framework/tools/_scripts/mosaic-migrate-local-skills.ps1

@@ -0,0 +1,90 @@
+# mosaic-migrate-local-skills.ps1
+# Migrates runtime-local skill directories to Mosaic-managed junctions.
+# Uses directory junctions (no elevation required) with fallback to copies.
+# PowerShell equivalent of mosaic-migrate-local-skills (bash).
+$ErrorActionPreference = "Stop"
+
+param(
+    [switch]$Apply,
+    [switch]$Help
+)
+
+$MosaicHome = if ($env:MOSAIC_HOME) { $env:MOSAIC_HOME } else { Join-Path $env:USERPROFILE ".config\mosaic" }
+$LocalSkillsDir = Join-Path $MosaicHome "skills-local"
+
+if ($Help) {
+    Write-Host @"
+Usage: mosaic-migrate-local-skills.ps1 [-Apply] [-Help]
+
+Migrate runtime-local skill directories (e.g. ~/.claude/skills/jarvis) to
+Mosaic-managed skills by replacing local directories with junctions to
+~/.config/mosaic/skills-local.
+
+Default mode is dry-run.
+"@
+    exit 0
+}
+
+if (-not (Test-Path $LocalSkillsDir)) {
+    Write-Host "[mosaic-local-skills] Missing local skills dir: $LocalSkillsDir" -ForegroundColor Red
+    exit 1
+}
+
+$skillRoots = @(
+    (Join-Path $env:USERPROFILE ".claude\skills"),
+    (Join-Path $env:USERPROFILE ".codex\skills"),
+    (Join-Path $env:USERPROFILE ".config\opencode\skills")
+)
+
+$count = 0
+
+Get-ChildItem $LocalSkillsDir -Directory | ForEach-Object {
+    $name = $_.Name
+    $src = $_.FullName
+
+    foreach ($root in $skillRoots) {
+        if (-not (Test-Path $root)) { continue }
+        $target = Join-Path $root $name
+
+        # Already a junction/symlink — check if it points to the right place
+        $existing = Get-Item $target -Force -ErrorAction SilentlyContinue
+        if ($existing -and ($existing.Attributes -band [System.IO.FileAttributes]::ReparsePoint)) {
+            $currentTarget = $existing.Target
+            if ($currentTarget -and ($currentTarget -eq $src -or (Resolve-Path $currentTarget -ErrorAction SilentlyContinue).Path -eq (Resolve-Path $src -ErrorAction SilentlyContinue).Path)) {
+                continue
+            }
+        }
+
+        # Only migrate local directories containing SKILL.md
+        if ((Test-Path $target -PathType Container) -and
+            (Test-Path (Join-Path $target "SKILL.md")) -and
+            -not ($existing -and ($existing.Attributes -band [System.IO.FileAttributes]::ReparsePoint))) {
+
+            $count++
+            if ($Apply) {
+                $stamp = Get-Date -Format "yyyyMMddHHmmss"
+                Rename-Item $target "$target.mosaic-bak-$stamp"
+                try {
+                    New-Item -ItemType Junction -Path $target -Target $src -ErrorAction Stop | Out-Null
+                    Write-Host "[mosaic-local-skills] migrated: $target -> $src"
+                }
+                catch {
+                    Write-Host "[mosaic-local-skills] Junction failed for $name, falling back to copy"
+                    Copy-Item $src $target -Recurse -Force
+                    Write-Host "[mosaic-local-skills] copied: $target <- $src"
+                }
+            }
+            else {
+                Write-Host "[mosaic-local-skills] would migrate: $target -> $src"
+            }
+        }
+    }
+}
+
+if ($Apply) {
+    Write-Host "[mosaic-local-skills] complete: migrated=$count"
+}
+else {
+    Write-Host "[mosaic-local-skills] dry-run: migratable=$count"
+    Write-Host "[mosaic-local-skills] re-run with -Apply to migrate"
+}