fix(kyberforge): bridge apm content to Claude Code's flat plugin discovery

Claude Code's (and Copilot's) native plugin installer has zero awareness of
.apm/ nesting -- it convention-scans only flat skills/, agents/, commands/,
hooks.json at each plugin's root. Confirmed via strings on the installed
claude binary and live installs of git@holocron/gitea@holocron/kyberforge@
holocron, all reporting Skills(0) Agents(0) Hooks(0) post ADR-0015's apm
conversion. Root cause (apm_cli/core/plugin_manifest.py): apm's plugin.json
compiler deliberately strips skills/agents/commands keys, assuming the host
already auto-discovers those convention directories -- it has no model of
.apm/ being host-visible at all. Separately, apm's own bundle exporter
(apm_cli/bundle/plugin_exporter.py, behind `apm pack --format plugin`)
implements the correct .apm/ -> flat mapping, but only ever targeted
build/<name>-<version>/, a path nothing in marketplace.json's source: points
at.

scripts/sync-plugin-content.sh wraps that bundle exporter and copies its
agents/, skills/, commands/, instructions/, extensions/, and merged
hooks.json back into each plugin's own root as a second tracked
compiled-output category -- same governance status as
.claude-plugin/plugin.json: generated from .apm/, never hand-edited. tests/
subdirectories are excluded from the mirror (dev fixtures, not host-visible
runtime content; several hardcode a relative repo-root walk-up sized for the
.apm/-nested depth, which breaks when duplicated one level shallower).
Applied for real across all 6 plugins and verified two ways: `claude plugin
validate --strict` passes on every real plugin directory, and a live
`claude --plugin-dir <path> -p "list skills/agents"` behavioral test
confirms content is now actually discovered.

Also, from the same issue #90 review round:
- scripts/check-manifests.sh pointed at each plugin's root-level plugin.json
  (checking skills/hooks/mcpServers/agents pointer fields) -- that file was a
  stale near-duplicate of .claude-plugin/plugin.json nothing else read or
  wrote, now deleted across all 6 plugins. check-manifests.sh is rewritten to
  validate .claude-plugin/plugin.json instead, and drops the pointer-field
  checks entirely (nothing to check -- those fields are correctly absent by
  design). Content-presence drift is now check-plugin-content-sync's job, a
  new pre-push hook wired in .pre-commit-config.yaml.

docs/adr/0017 records the root cause and decision in full, including two
rejected alternatives (patching plugin.json's path fields directly -- apm's
compiler strips them on every run; pointing marketplace.json at apm pack's
build/ output -- a version-suffixed non-source directory nothing can install
from without an extra build step). ADR-0015 and CONTEXT.md are updated to
point at it.

Refs: #90

plugins/gitea/skills/gitea-issues/references/search.md

@@ -0,0 +1,39 @@
+---
+topic: search
+source_keys:
+  - gitea-mcp-repo
+  - gitea-mcp-slim-go
+---
+
+# `search_issues`
+
+Call signature verified live against the deployed `gitea-mcp` server via `ToolSearch` at authoring
+time (see `references/sources.md`) — confirmed to match `api-reference.md`.
+
+**Parameters:**
+- `query` (string, required) — the only hard-required parameter
+- `state` (string, enum `"open"` | `"closed"` | `"all"`, optional)
+- `type` (string, enum `"issues"` | `"pulls"`, optional) — **this tool has a working type filter**,
+  unlike `list_issues` (see `references/issues.md`)
+- `labels` (string, optional) — comma-separated label **names** — a plain string, not the array form
+  `list_issues` uses
+- `owner` (string, optional) — restrict results to one owner
+- `page` (number, optional, default `1`)
+- `per_page` (number, optional, default `30`)
+
+**Call:**
+```
+search_issues query: <text>
+```
+
+**Narrowing the search:**
+```
+search_issues query: <text> owner: <owner> state: "open" type: "pulls" labels: "bug,urgent"
+```
+
+This is a cross-repository search (unlike `list_issues`, which is scoped to one `owner`/`repo`) —
+useful when the caller doesn't know which repo an issue lives in, or wants results across an
+organization. Pass `owner` to narrow scope if the caller does know it.
+
+Paginate the same way as `list_issues`: iterate `page` until the returned count is less than
+`per_page`.