feat(dev-fkeys): add project-aware F4 compile/run dispatcher

I added a new module `modules/dev-fkeys.el` that owns the dev F-key block. F4 prompts via `completing-read` with a candidate set filtered by project type (compiled / interpreted / unknown). C-F4 is the compile-only fast path. M-F4 is clean + rebuild. It runs a heuristic clean command derived from the project markers (go.mod, Cargo.toml, Eask, Makefile, CMakeLists.txt) and chains `projectile-compile-project` on success. S-F4 stays on `recompile` and now lives globally instead of duplicated across prog-general.el and prog-c.el. F6 is bound globally to `projectile-test-project` as a Phase 1 stopgap. Phase 2 replaces it with the polyglot test runner spec'd in todo.org.

Project-type detection runs against the projectile root and falls back to `unknown` when no marker matches. Interpreted markers are checked first so a Python or Node project with a Makefile for tasks classifies as interpreted instead of compiled. Compile + Run sequencing uses a one-shot `compilation-finish-functions` hook that self-removes on first invocation and only fires the follow-up when the status string starts with `finished`.

Cleanup in the same commit:
- Dropped F4/F5/F6 from `prog-general.el`'s prog-mode-hook. They are now global.
- Dropped F6→format bindings from prog-c.el / prog-python.el / prog-shell.el. C-; f was already bound in each, so this is pure removal.
- Dropped the duplicate S-F4 from prog-c.el. The global binding covers it.
- Updated the keybinding header in prog-general.el and the workflow comments in prog-c.el / prog-shell.el.
- Wired `(require 'dev-fkeys)` in init.el alongside coverage-core.

TDD: 73 tests across 11 files, one per helper. Production code is split into small testable internals (`cj/--detect-project-type`, `cj/--f4-candidates`, `cj/--f4-derive-clean-cmd`, `cj/--f4-make-once-hook`, `cj/--f4-dispatch`, `cj/--f4-compile-and-run-impl`, `cj/--f4-clean-rebuild-impl`, `cj/--f4-project-root`) plus three thin interactive wrappers. Smoke tests confirm bindings register on load.

Known limitation: if another `compilation-finish-functions` hook fires between my add-hook and the compile finishing, the chain can fire on the wrong compile. The hook self-removes on first invocation regardless of which compile it sees. Documented in the impl docstring. Acceptable for v1.

Phase 2 will replace F6 with the polyglot test runner (tree-sitter queries for Python/Go/TS, sexp scan for Elisp, buffer-local last-test memory).

1 files changed, 51 insertions, 0 deletions

diff --git a/tests/test-dev-fkeys--f4-project-root.el b/tests/test-dev-fkeys--f4-project-root.el
new file mode 100644
index 00000000..617bb9e1
--- /dev/null
+++ b/tests/test-dev-fkeys--f4-project-root.el
@@ -0,0 +1,51 @@
+;;; test-dev-fkeys--f4-project-root.el --- Tests for cj/--f4-project-root -*- lexical-binding: t -*-
+
+;;; Commentary:
+;; Tests for the projectile-root wrapper. Projectile's
+;; `projectile-project-root' raises an error in some configurations when
+;; called outside a known project; this wrapper degrades to nil so the F4
+;; dispatcher can route to the 'unknown branch instead of crashing.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'dev-fkeys)
+
+;;; Normal Cases
+
+(ert-deftest test-dev-fkeys-f4-project-root-returns-projectile-value ()
+  "Normal: returns whatever `projectile-project-root' returns when fbound."
+  (cl-letf (((symbol-function 'projectile-project-root)
+             (lambda () "/some/project/")))
+    (should (string= (cj/--f4-project-root) "/some/project/"))))
+
+;;; Boundary Cases
+
+(ert-deftest test-dev-fkeys-f4-project-root-returns-nil-when-projectile-unbound ()
+  "Boundary: returns nil when projectile is not loaded.
+
+Components integrated:
+- `cj/--f4-project-root' (unit under test)
+- `projectile-project-root' (MOCKED — fmakunbound to simulate absence)"
+  (let ((had-projectile (fboundp 'projectile-project-root))
+        (saved (and (fboundp 'projectile-project-root)
+                    (symbol-function 'projectile-project-root))))
+    (unwind-protect
+        (progn
+          (when had-projectile (fmakunbound 'projectile-project-root))
+          (should (null (cj/--f4-project-root))))
+      (when had-projectile
+        (fset 'projectile-project-root saved)))))
+
+;;; Error Cases
+
+(ert-deftest test-dev-fkeys-f4-project-root-returns-nil-on-projectile-error ()
+  "Error: returns nil when `projectile-project-root' signals an error."
+  (cl-letf (((symbol-function 'projectile-project-root)
+             (lambda () (error "Outside a known project"))))
+    (should (null (cj/--f4-project-root)))))
+
+(provide 'test-dev-fkeys--f4-project-root)
+;;; test-dev-fkeys--f4-project-root.el ends here