fix(plugin): every hook's credential + URL encoding was broken

Three defects, each of which independently made a hook a no-op, and all
three failing silently — which is why the whole dynamic side of the plugin
looked "shipped" while doing nothing.

1. Wrong env var case. Claude Code exports userConfig to hooks as
   CLAUDE_PLUGIN_OPTION_<KEY> with the key UPPERCASED. All four hooks read
   CLAUDE_PLUGIN_OPTION_api_endpoint / _api_token, so both values were
   always empty. That killed the SessionStart dynamic tier, process sync,
   prompt auto-inject, and the write-path prior-art trigger at once.

2. jq -rR is line-oriented. `@uri` under -R encodes input LINE BY LINE, so
   a multi-line payload came back as several encoded lines joined by raw
   newlines — an invalid URL, curl fails, hook exits 0 in silence. Now
   -sRr. This one hid behind (1): auto-inject only ever worked for
   single-line prompts, and prior-art (which posts code, always
   multi-line) could never have worked at all.

3. cut -c1-1200 caps each LINE, not the payload, so the prior-art code
   budget wasn't a budget. Now head -c 1200.

Also widens the SessionStart warning: "neither URL nor token arrived" used
to be treated as a benign unconfigured install and stayed quiet. That is
exactly the state defect (1) produced, so the one install state that most
needed a signal was the only one that emitted none. It now says so, and
names the two other features it silently disables.

Verified against the live instance: dynamic rules + project context load,
auto-inject surfaces #2192 on a multi-line prompt, and the write-path
trigger returns the [here] place-arm hit on a multi-line edit with session
dedup suppressing the repeat.

Refs #2198, #2082

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UaYUaouG9jjhATyuxCKrQs

plugin/hooks/scribe_autoinject.sh

@@ -11,9 +11,12 @@
 # static floor here. If the instance is unconfigured/unreachable, or anything
 # fails, the hook stays SILENT and exits 0 — it must never block a prompt.
 #
-# Config (same as scribe_session_context.sh), exported to the hook by Claude Code:
-#   CLAUDE_PLUGIN_OPTION_api_endpoint  base URL, no trailing slash
-#   CLAUDE_PLUGIN_OPTION_api_token     fmcp_ API key (sensitive)
+# Config (same as scribe_session_context.sh), exported to the hook by Claude Code
+# with the userConfig key UPPERCASED (see #2198 — reading the lowercase spelling
+# silently disables this hook, and silence is indistinguishable from "nothing
+# cleared the threshold"):
+#   CLAUDE_PLUGIN_OPTION_API_ENDPOINT  base URL, no trailing slash
+#   CLAUDE_PLUGIN_OPTION_API_TOKEN     fmcp_ API key (sensitive)
 #   SCRIBE_URL / SCRIBE_TOKEN override for the settings.json dogfooding path.
 #
 # Session dedup: each surfaced note id is remembered in a per-session file so a
@@ -32,8 +35,8 @@ event_cwd=$(printf '%s' "$event" | jq -r '.cwd // empty' 2>/dev/null) || event_c
 # Nothing to retrieve against.
 [ -n "$prompt" ] || exit 0
 
-url=${SCRIBE_URL:-${CLAUDE_PLUGIN_OPTION_api_endpoint:-}}
-token=${SCRIBE_TOKEN:-${CLAUDE_PLUGIN_OPTION_api_token:-}}
+url=${SCRIBE_URL:-${CLAUDE_PLUGIN_OPTION_API_ENDPOINT:-}}
+token=${SCRIBE_TOKEN:-${CLAUDE_PLUGIN_OPTION_API_TOKEN:-}}
 # Guard against an unexpanded ${...} placeholder arriving as a literal.
 case "$url"   in *'${'*) url="" ;;  esac
 case "$token" in *'${'*) token="" ;; esac
@@ -42,14 +45,18 @@ case "$token" in *'${'*) token="" ;; esac
 
 # Cap the query length — a giant prompt makes a giant URL for no extra signal.
 q=$(printf '%s' "$prompt" | cut -c1-2000)
-q_enc=$(printf '%s' "$q" | jq -rR '@uri' 2>/dev/null) || exit 0
+# `-sRr`, not `-rR`: jq -R reads LINE BY LINE, so a multi-line prompt encoded as
+# several lines joined by raw newlines and the request died. Single-line prompts
+# worked, which is why this looked healthy — the long, substantial prompts most
+# worth retrieving against were exactly the ones silently dropped. -s slurps.
+q_enc=$(printf '%s' "$q" | jq -sRr '@uri' 2>/dev/null) || exit 0
 
 # Resolve the working repo's remote so the server can scope to the bound project.
 repo_dir=${event_cwd:-${CLAUDE_PROJECT_DIR:-$PWD}}
 repo=$(git -C "$repo_dir" remote get-url origin 2>/dev/null || true)
 repo_q=""
 if [ -n "$repo" ]; then
-  enc=$(printf '%s' "$repo" | jq -rR '@uri' 2>/dev/null) || enc=""
+  enc=$(printf '%s' "$repo" | jq -sRr '@uri' 2>/dev/null) || enc=""
   [ -n "$enc" ] && repo_q="&repo=${enc}"
 fi