Show a profile-grounding indicator on the planning screen

The planning view renders a quiet line for the standing-profile state
(loading/grounded/absent/unreadable) with a "change" affordance to
repoint the file via POST /knowledge/path. The profile text never
reaches the browser — only status, path, and size. Also updates the
README Status section to describe the M6 knowledge port.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

README.md

@@ -23,6 +23,17 @@ go test ./...
 
 ## Status
 
+M6 (knowledge port): the planning coach now sharpens intents against who you
+actually are. A single profile file (`~/.antidrift/knowledge.md`, overridable
+via `ANTIDRIFT_KNOWLEDGE_FILE`) holds your standing context — priorities,
+values, what counts as good work — and the daemon loads it asynchronously on
+entering planning, mirroring the tasks fetch. The cached text grounds the AI
+coach prompt only; the drift judge and nudge are untouched, and the profile text
+never crosses the wire. A subtle planning-screen indicator shows whether the
+profile loaded and from where, with a "change" affordance to repoint at another
+file. It degrades gracefully — a missing, blank, or unreadable file just leaves
+the coach ungrounded, and planning still works.
+
 M3.5 (semantic nudge): the drift interceptor catches the *wrong app*, but not
 the *wrong work inside a right app*. M3.5 adds a third, ambient AI role that —
 only while you are on-task in an allowed app — periodically reads your recent