chore(release): kyberforge 1.5.0, marketplace 0.4.0

Why
---
The SessionStart freshness hook is a new kyberforge feature and was committed
without a version bump. It also cannot ship unbumped: apm's executable-trust
allow key is version-pinned, so `kyberforge#1.4.1` would have stopped matching
the moment the package version moved, silently blocking the very hook the entry
exists to authorise.

Implementation notes
-----------------
kyberforge 1.4.1 -> 1.5.0 (MINOR, new feature); marketplace and root manifest
0.3.4 -> 0.4.0, following the convention in bb9158d where a package bump carries
the marketplace version with it. The executables.allow key moves to
kyberforge#1.5.0 in the same commit. Compiled manifests regenerated with
`apm pack` plus both sync scripts.

A bare `apm pack` also writes build/ and a root .claude-plugin/plugin.json,
neither of which is repo content — the pre-push gate only ever runs pack with
--dry-run, so they had not appeared before. Both removed; build/ is now
gitignored so a future release does not stage it by accident.

Impact
------
Consumers pinning kyberforge see a MINOR bump. All 15 pre-push hooks pass,
including apm pack --check-clean, so compiled output matches the manifests.

ADR: 0019

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01X7GvKuJfy2WrdBmUttV4DT

.claude-plugin/marketplace.json

@@ -1,7 +1,7 @@
 {
   "name": "holocron",
   "description": "AI development skills for Claude Code and GitHub Copilot CLI — factory, design, implement, review, and cross-cutting workflows.",
-  "version": "0.3.4",
+  "version": "0.4.0",
   "owner": {
     "name": "Defame1297",
     "email": "defame1297@rkdr.net",
@@ -11,7 +11,7 @@
     {
       "name": "kyberforge",
       "description": "Skills and agents for creating, maintaining, and managing a Claude Code / Copilot CLI plugin marketplace.",
-      "version": "1.4.1",
+      "version": "1.5.0",
       "category": "Developer Tools",
       "source": "./plugins/kyberforge"
     },