docs(roadmap): add Mermaid Gantt and split version detail into roadmap.md

Macro-plan dates start 2026-06-01 with `after` dependencies between
versions. Per-version checklists move to docs/roadmap.md so the README
stays synthetic.

docs/roadmap.md

@@ -0,0 +1,100 @@
+# Roadmap — version details
+
+Frequent releases. Each version is a usable artifact, not a checkpoint.
+The macro-plan (Gantt) lives in the [README](../README.md#roadmap); this file
+holds the per-version scope.
+
+---
+
+## v0.1 — MVP: "it writes, it pushes" — [ ]
+
+The minimum thing that justifies the hardware existing. Full design:
+[product](v0.1-mvp-product.md) · [technical](v0.1-mvp-technical.md).
+
+- [ ] ESP32-S3 boots, e-ink shows splash + boot log
+- [ ] USB host enumerates the Nuphy, key events reach the editor
+- [ ] One hard-coded file (`/sd/repo/notes.md`) opens on boot
+- [ ] Insert-only editing (no modes yet), backspace, enter, arrow keys
+- [ ] Line wrap, no line numbers yet
+- [ ] Save on `Ctrl-S` → SD
+- [ ] Wi-Fi credentials via captive portal on first boot, stored in NVS
+- [ ] `Ctrl-G` runs: `git add notes.md && git commit -m "wip" && git push` to a
+      pre-configured remote, using a PAT entered during setup
+- [ ] Partial refresh on edits; full refresh on save
+
+Out of scope: Vim, palette, multiple files, branches, conflict handling.
+
+## v0.2 — Vim navigation — [ ]
+
+- [ ] Mode state machine (Normal / Insert), mode indicator in status line
+- [ ] Movement: `h j k l`, `w b e`, `0 $`, `gg G`, `Ctrl-d Ctrl-u`
+- [ ] `i a o O A` to enter Insert
+- [ ] `Esc` returns to Normal
+- [ ] Line numbers (absolute) in the left gutter
+
+## v0.3 — Vim editing — [ ]
+
+- [ ] `x dd yy p P`, `dw dd d$`, repeat with `.`
+- [ ] Undo / redo (`u`, `Ctrl-r`) — bounded history in PSRAM
+- [ ] Numeric prefixes (`3dd`, `5j`)
+
+## v0.4 — Visual mode + ex commands — [ ]
+
+- [ ] Visual char (`v`) and line (`V`) modes, `y d c` on selections
+- [ ] `:` command line: `:w :q :wq :e <path>`
+- [ ] Status line shows file path, dirty flag, mode
+
+## v0.5 — File palette + multi-file — [ ]
+
+- [ ] `Ctrl-P` opens fuzzy file palette over **both** `/sd/repo/` and
+      `/sd/local/`, with a scope marker (e.g. `[git]` / `[local]`) per result
+- [ ] Open, switch, close buffers (keep ≤ 3 in memory)
+- [ ] `:e` and palette share the same recent-files list
+- [ ] `:enew` creates a new file — prompts for scope (tracked vs local)
+- [ ] `Ctrl-G` is disabled / hidden when the current buffer is local-scope
+
+## v0.6 — Markdown affordances — [ ]
+
+- [ ] Heading lines bolded in render
+- [ ] List continuation on Enter inside `- ` / `1. `
+- [ ] Soft-wrap at word boundaries
+- [ ] Optional column ruler at 80
+
+## v0.7 — Search + better git — [ ]
+
+- [ ] `/` forward search, `n N`
+- [ ] `:Gpull` (fetch + fast-forward only; refuse on conflict and surface it)
+- [ ] `:Gbranch` to switch branches; refuse with dirty tree
+- [ ] Commit message prompt instead of hard-coded `"wip"`
+
+## v0.8 — Power: battery + sleep — [ ]
+
+- [ ] Measure idle / typing / push current draw on bench
+- [ ] 18650 + IP5306 charge board, soft power switch
+- [ ] Light sleep on idle > 30 s (keyboard interrupt wakes)
+- [ ] Deep sleep on lid close (reed switch); restore cursor + buffer
+- [ ] Battery indicator in status line
+
+## v0.9 — Robustness — [ ]
+
+- [ ] Crash-safe writes (write to `.tmp`, fsync, rename)
+- [ ] Recover from interrupted push (re-attempt on next save)
+- [ ] SD card removal / reinsert handling
+- [ ] Wi-Fi reconnect with backoff
+- [ ] Settings screen: SSID, PAT rotation, default remote, commit author
+
+## v1.0 — Polish — [ ]
+
+- [ ] Boot time ≤ 3 s to usable cursor
+- [ ] Font selection (at least one serif + one mono)
+- [ ] Enclosure design files in `hardware/`
+- [ ] User guide
+
+## v1.x — Stretch / nice-to-have
+
+- 10.3" panel upgrade via IT8951
+- Multiple remotes / repos
+- Spell-check (dictionary in flash, naive)
+- Stats: words today, streak
+- Theme: light / dark (inverted e-ink)
+- BLE-HID fallback for wireless keyboards