feat(timeline): rename --expand-mentions to --no-mentions, default mentions on

Invert the timeline mention-expansion flag semantics. Previously, mention
edges were excluded by default and --expand-mentions opted in. Now mention
edges are included by default (matching the more common use case) and
--no-mentions opts out to reduce fan-out when needed.

This is a breaking CLI change but aligns with the principle that the
default behavior should produce the most useful output. Users who were
passing --expand-mentions get the same behavior without any flag. Users
who want reduced output can pass --no-mentions.

Updated: CLI args (TimelineArgs), autocorrect flag list, robot-docs
schema, README documentation and flag reference table.

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

README.md

@@ -400,7 +400,7 @@ lore timeline m:99                            # Shorthand for mr:99
 lore timeline "auth" -p group/repo           # Scoped to a project
 lore timeline "auth" --since 30d             # Only recent events
 lore timeline "migration" --depth 2          # Deeper cross-reference expansion
-lore timeline "migration" --expand-mentions  # Follow 'mentioned' edges (high fan-out)
+lore timeline "migration" --no-mentions      # Skip 'mentioned' edges (reduces fan-out)
 lore timeline "deploy" -n 50                 # Limit event count
 lore timeline "auth" --max-seeds 5           # Fewer seed entities
 ```
@@ -414,7 +414,7 @@ The query can be either a search string (hybrid search finds matching entities)
 | `-p` / `--project` | all | Scope to a specific project (fuzzy match) |
 | `--since` | none | Only events after this date (7d, 2w, 6m, YYYY-MM-DD) |
 | `--depth` | `1` | Cross-reference expansion depth (0 = seeds only) |
-| `--expand-mentions` | off | Also follow "mentioned" edges during expansion |
+| `--no-mentions` | off | Skip "mentioned" edges during expansion (reduces fan-out) |
 | `-n` / `--limit` | `100` | Maximum events to display |
 | `--max-seeds` | `10` | Maximum seed entities from search |
 | `--max-entities` | `50` | Maximum entities discovered via cross-references |
@@ -427,7 +427,7 @@ Each stage displays a numbered progress spinner (e.g., `[1/3] Seeding timeline..
 
 1. **SEED** -- Hybrid search (FTS5 lexical + Ollama vector similarity via Reciprocal Rank Fusion) identifies the most relevant issues and MRs. Falls back to lexical-only if Ollama is unavailable. Discussion notes matching the query are also discovered and attached to their parent entities.
 2. **HYDRATE** -- Evidence notes are extracted: the top search-matched discussion notes with 200-character snippets explaining *why* each entity was surfaced. Matched discussions are collected as full thread candidates.
-3. **EXPAND** -- Breadth-first traversal over the `entity_references` graph discovers related entities via "closes", "related", and optionally "mentioned" references up to the configured depth.
+3. **EXPAND** -- Breadth-first traversal over the `entity_references` graph discovers related entities via "closes", "related", and "mentioned" references up to the configured depth. Use `--no-mentions` to exclude "mentioned" edges and reduce fan-out.
 4. **COLLECT** -- Events are gathered for all discovered entities. Event types include: creation, state changes, label adds/removes, milestone assignments, merge events, evidence notes, and full discussion threads. Events are sorted chronologically with stable tiebreaking.
 5. **RENDER** -- Events are formatted as human-readable text or structured JSON (robot mode).
 

src/cli/autocorrect.rs

@@ -166,7 +166,7 @@ const COMMAND_FLAGS: &[(&str, &[&str])] = &[
             "--project",
             "--since",
             "--depth",
-            "--expand-mentions",
+            "--no-mentions",
             "--limit",
             "--fields",
             "--max-seeds",