#3649: docs: remove numeric model selection references and document /models

## Summary - Update `/model` docs to reflect summary view and alias/provider syntax - Remove numbered picker and `/model <#>` references - Add `/models` and `/models <provider>` guidance ## Why PR #1398 (Jan 21, 2026) removed numeric model selection from chat, but the docs were never updated. Users see `/model 3` in docs but get "Numeric model selection is not supported in chat" when they try it. ## Files Changed - `docs/concepts/models.md` - `docs/tools/slash-commands.md` - `docs/help/faq.md` ## Testing - [x] Docs-only change, no code testing needed - [x] Verified examples match current `/model` behavior ## AI Disclosure 🤖 This PR was drafted with Claude (Opus 4.5) assistance. The changes are straightforward docs updates that I understand and have verified against the actual code behavior. <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> Docs update aligns model-selection guidance with current chat behavior: removes numeric `/model <#>` examples, documents `/model` summary + `provider/model` and alias usage, and introduces `/models` / `/models <provider>` discovery guidance. Main inconsistency spotted: the slash-command list still claims `/models` is an alias of `/model`, which conflicts with the new `/models` semantics. <h3>Confidence Score: 4/5</h3> - This PR is safe to merge with minimal risk, but has a couple doc inconsistencies that should be corrected. - Docs-only changes and the intent is clear, but there are conflicting statements about `/models` (alias vs distinct command) and some leftover `/model list` references that could mislead users. - docs/tools/slash-commands.md (command list entry) and docs/help/faq.md (remaining `/model list` references). <!-- greptile_other_comments_section --> _{(3/5) Reply to the agent's comments like "Can you suggest a fix for this @greptileai?" or ask follow-up questions!} <!-- /greptile_comment -->