refactor: retire unreferenced modules to an archive directory

A reachability sweep from init.el found eight .el files that nothing in the config loads or references. I moved them under archive/ (off the load-path, still tracked in git) so they stay readable and restorable rather than deleted. archive/README.org records the rule (every .el outside archive/ should be actively used) and why each file was retired.

I retired show-kill-ring, duet-config, and mu4e-org-contacts-setup from modules/, and eplot, profile-dotemacs, titlecase, titlecase-data, and edit-indirect from custom/. Retiring show-kill-ring also removed the orphaned M-K -> M-S-k translation in keyboard-compat, which had left M-K a dead key. Its tests now assert seventeen translations and guard M-K's absence.

1 files changed, 64 insertions, 0 deletions

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+#+TITLE: Archive — Retired Modules
+#+AUTHOR: Craig Jennings
+
+* What this is
+
+The pasture upstate. Modules that were once part of the config but are no
+longer loaded, kept here instead of deleted so they can be read, mined for
+ideas, or brought back later.
+
+Nothing in this directory is on the Emacs =load-path=, and nothing in the
+active config requires anything here. Retiring a file means moving it here and
+removing whatever orphaned reference kept pointing at it. Restoring one means
+moving it back to =modules/= or =custom/= and re-adding its =require= (or
+=use-package=) in =init.el=.
+
+The directory is tracked in git, so every retired file stays retrievable from
+history even after it moves again.
+
+* The rule this directory enforces
+
+Every =.el= file *outside* this directory should be of active use — required,
+loaded, or otherwise reached by the running config. If a file is never touched,
+loaded, or referenced, it belongs here. The candidate list is generated by a
+reachability sweep from =init.el= (transitive =require= closure), then checked
+by hand for the cases pure requires miss: =use-package= with =:load-path=,
+autoloads, and vendored copies shadowed by a package-manager install.
+
+* Layout
+
+Retired files keep their origin directory so a restore is a straight move back:
+
+- =archive/modules/= — retired first-party modules
+- =archive/custom/= — retired vendored third-party files
+- =archive/tests/= — tests belonging to retired modules
+- =archive/gptel/= — the gptel feature subtree, retired as a unit
+
+* Inventory
+
+** archive/modules/
+
+- =show-kill-ring.el= — kill-ring viewer bound to M-S-k. Its =require= was
+  dropped in b785a19d and consult-yank-pop covers the same need. Retiring it
+  also removed the orphaned M-K -> M-S-k translation in =keyboard-compat.el=,
+  which had been leaving M-K a dead key.
+- =duet-config.el= — no reference anywhere in the config.
+- =mu4e-org-contacts-setup.el= — nothing requires it; its featurep gate would
+  be nil at init in any case. The live mu4e contacts wiring lives in
+  =mu4e-org-contacts-integration.el=.
+
+** archive/custom/
+
+- =eplot.el= — vendored plotting package, unreferenced.
+- =profile-dotemacs.el= — startup-profiling tool, unreferenced.
+- =titlecase.el= + =titlecase-data.el= — the duckwork/titlecase.el package,
+  superseded by =custom-case.el='s own =cj/title-case-region=.
+- =edit-indirect.el= — a vendored copy of the MELPA package that
+  =text-config.el= installs (its =use-package= carries no =:ensure nil=). With
+  this copy off the =load-path=, the MELPA copy loads, which is the intended
+  one.
+
+** archive/gptel/
+
+The gptel AI-assistant feature, retired as a whole subtree (modules, tests,
+tools, custom, and its spec docs) when the config moved off gptel.