fix(factory-audit): flag unbraced plugin-root tokens and close hook check gaps

Why: PR #144 review round 4 reproduced hooks referencing $PLUGIN_ROOT or
${PLUGIN_ROOT} without a path separator passing the audit, although apm
only rewrites ${TOKEN}/ and the deployed hook points nowhere.

- FAIL unbraced or unseparated plugin-root tokens
- check the exec bit for scripts run via an interpreter -c string
- skip env NAME=value prefixes when locating bare relative paths
- correct input: and empty-frontmatter messages, depth-walk applyTo braces
- INFO on unrecognised targets; failing-case tests for untested checks
- document tiers, blind spots and crash exit 2; drop rtk from portable flow
- restore the after-a-hand-edit trigger; pin upstream apm source URL

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KkT7RSDwDbmrM9T34b6sTi

plugins/kyberforge/.apm/skills/factory-audit/references/prompt-flow.md

@@ -12,7 +12,7 @@ order, then return to `SKILL.md` Step 4 to report.
 
 ## Gotchas
 
-- A prompt is judged against ADR-0029, not against apm's framing. apm calls a prompt "a callable program"; this repo holds it to a single-intent, user-triggered message that steers existing skills or agents by name and carries no procedure of its own.
+- A prompt is judged against ADR-0029, not against apm's framing. apm's docs call a prompt "a program for an LLM" (`apm-docs-llms-full`, "What is APM?" › "Secure by default"); this repo holds it to a single-intent, user-triggered message that steers existing skills or agents by name and carries no procedure of its own.
 - A prompt's description is not a skill description. It is one plain user-facing sentence with no "Use when" trigger clause and no boundary clause — so never raise a missing trigger or boundary as a finding. A Vale `Kyberforge.DescriptionOpener` alert here means rewrite it as an imperative action ("Review the current PR with …"), not add a trigger.
 
 ## Step 1 — Deterministic checks
@@ -24,7 +24,7 @@ bash scripts/validate.sh <prompt-file>
 bash scripts/vale-wrap.sh <prompt-file>
 ```
 
-`validate.sh` findings become the `### Structure` dimension, FAILs and SUGGESTIONs both, at the tier the script assigned: path and name, unfilled `FILL IN` or `FILL_IN_` template placeholders, frontmatter, `description` presence, length, and trigger or `Not X -> Y` boundary clause, keys Claude drops, the camelCase spelling of `allowed-tools` or `argument-hint` and an `argument-hint` alongside `input:` (both SUGGESTION), `input:` names and the object form `- <name>: "<desc>"` (`primitive-author` prompt Must 3 — a bare name, a string list or a plain map is a FAIL even though apm reads them), and `${input:x}` references against `input:`. Keys Claude drops are a SUGGESTION, per `primitive-author` prompt Should 5: a Copilot-only key is legitimate when its Claude drop is intended, and only the author can say which. It exits **0** with no FAIL, **1** on real findings, **2** when it never ran — report that as `### Structure` unverified, quoting the stderr reason.
+`validate.sh` findings become the `### Structure` dimension, FAILs and SUGGESTIONs both, at the tier the script assigned: path and name, a file that is not valid UTF-8, unfilled `FILL IN` or `FILL_IN_` template placeholders, frontmatter, `description` presence, length, and trigger or `Not X -> Y` boundary clause, keys Claude drops, the camelCase spelling of `allowed-tools` or `argument-hint` and an `argument-hint` alongside `input:` (both SUGGESTION), `input:` names and the object form `- <name>: "<desc>"` (`primitive-author` prompt Must 3 — a bare name, a string list or a plain map is a FAIL even though apm reads them), and `${input:x}` references against `input:`. Keys Claude drops are a SUGGESTION, per `primitive-author` prompt Should 5: a Copilot-only key is legitimate when its Claude drop is intended, and only the author can say which. It exits **0** with no FAIL, **1** on real findings, **2** when it never ran, including a crash inside the checks — report that as `### Structure` unverified, quoting the stderr reason.
 
 `vale-wrap.sh` applies the bundled `Kyberforge` style. Every alert is a FAIL under `### Prose`, cited by rule ID; do not re-derive it by judgment. That includes the rules scoped to the `description` (`Kyberforge.DescriptionOpener`, `VagueWording`, `CompositionNote`), a deliberate deviation from `primitive-author`, which holds description wording to at most a Should: the house prose rules apply to every model- or user-visible description, and a deterministic rule does not change tier by file kind. Do not re-tier them. `0 files` scanned means NOT RUN, not clean — say so and judge prose by reading.