fix(archive): derive <company>_<role> as a single path component (#329)

Extends the canonical Subfolder-naming rule by citation to all six archive derivation sites (apply, gmail-sync, interview, notion-sync, outcome, assistant SKILL.md), adds a fail-closed guard for an empty derived name, and pins every site with mutation-verified tests. framework_version 1.3.3 -> 1.3.4.

jakob1379 independently specified the same fix in his fork's issue #22 before this PR's rework.

Co-authored-by: ayobamiseun <66267222+ayobamiseun@users.noreply.github.com>

.claude/skills/job-application-assistant/SKILL.md

@@ -5,7 +5,7 @@ description: >
   and preparing for interviews. Triggers on keywords like: job posting, job application, CV,
   cover letter, resume, interview prep, job fit, career, application, apply, ansøgning, stilling
 allowed-tools: Read, Glob, Grep, WebFetch, WebSearch, Bash, Edit, Write, AskUserQuestion
-framework_version: 1.3.3
+framework_version: 1.3.4
 ---
 
 # Job Application Assistant
@@ -27,6 +27,7 @@ When the user provides a job posting (URL or text), follow this workflow:
 - Ask the user if they want to proceed with an application
 
 ### Step 2: Tailor CV
+- Before writing either document, derive `<company>_<role>` once by the **Subfolder naming** rule in `documents/README.md`; reuse that exact value for the CV, cover letter, and Step 3b archive path. If the rule says to stop because the derived name is empty, stop before creating any file.
 - Read the most relevant existing CV variant from `cv/` as a starting point
 - Follow the guidelines in `05-cv-templates.md`
 - Create `cv/main_<company>_<role>.tex` with tailored content