docs: add feature ideas catalog, time-decay scoring plan, and timeline issue doc

Ideas catalog (docs/ideas/): 25 feature concept documents covering future
lore capabilities including bottleneck detection, churn analysis, expert
scoring, collaboration patterns, milestone risk, knowledge silos, and more.
Each doc includes motivation, implementation sketch, data requirements, and
dependencies on existing infrastructure. README.md provides an overview and
SYSTEM-PROPOSAL.md presents the unified analytics vision.

Plans (plans/): Time-decay expert scoring design with four rounds of review
feedback exploring decay functions, scoring algebra, and integration points
with the existing who-expert pipeline.

Issue doc (docs/issues/001): Documents the timeline pipeline bug where
EntityRef was missing project context, causing ambiguous cross-project
references during the EXPAND stage.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/ideas/idle.md

@@ -0,0 +1,69 @@
+# Idle Work Detector
+
+- **Command:** `lore idle [--days <N>] [--labels <pattern>]`
+- **Confidence:** 73%
+- **Tier:** 3
+- **Status:** proposed
+- **Effort:** medium — label event querying with configurable patterns
+
+## What
+
+Find entities that received an "in progress" or similar label but have had no
+discussion activity for N days. Cross-reference with assignee to show who might
+have forgotten about something.
+
+## Why
+
+Forgotten WIP is invisible waste. Developers start work, get pulled to something
+urgent, and the original task sits idle. This makes it visible before it becomes
+a problem.
+
+## Data Required
+
+All exists today:
+- `resource_label_events` (label_name, action='add', created_at)
+- `discussions` (last_note_at for entity activity)
+- `issues` / `merge_requests` (state, assignees)
+- `issue_assignees` / `mr_assignees`
+
+## Implementation Sketch
+
+```
+1. Query resource_label_events for labels matching "in progress" patterns
+   Default patterns: "in-progress", "in_progress", "doing", "wip",
+   "workflow::in-progress", "status::in-progress"
+   Configurable via --labels flag
+2. For each entity with an "in progress" label still applied:
+   a. Check if the label was subsequently removed (if so, skip)
+   b. Get last_note_at from discussions for that entity
+   c. Flag if last_note_at is older than threshold
+3. Join with assignees for attribution
+```
+
+## Human Output
+
+```
+Idle Work (labeled "in progress" but no activity for 14+ days)
+
+group/backend
+  #90  Rate limiting design       assigned to: charlie    idle 18 days
+       Last activity: label +priority::high by dave
+  #85  Cache invalidation fix     assigned to: alice      idle 21 days
+       Last activity: discussion comment by bob
+
+group/frontend
+  !230 Dashboard redesign         assigned to: eve        idle 14 days
+       Last activity: DiffNote by dave
+```
+
+## Downsides
+
+- Requires label naming conventions; no universal standard
+- Work may be happening outside GitLab (local branch, design doc)
+- "Idle" threshold is subjective; 14 days may be normal for large features
+
+## Extensions
+
+- `lore idle --assignee alice` — personal idle work check
+- `lore idle --notify` — generate message templates for nudging owners
+- Configurable label patterns in config.json for team-specific workflows