Summary

The workflow canvas editor's agent-config panel (NodeConfigPanel in CanvasPage.tsx — the "右侧智能体弹窗" shown when editing an agent node) was a floating popup pinned to the canvas's top-right corner, overlaying nodes, with a cramped fixed width and a tiny non-resizable prompt textarea.
This reworks it into a docked, resizable sidebar with a larger prompt editor.

Changes

#6154 — dock the panel as a horizontally-resizable sidebar

The panel now renders as a flex sibling of the canvas <main> on the right edge, so the canvas shrinks to make room instead of being overlaid by an absolutely-positioned popup.
A left-edge drag handle resizes the panel horizontally using plain pointer events with pointer capture (no new dependency); during the drag the width updates frame-by-frame in local state and the final value is committed on pointer-up.
The chosen width is clamped to 300–720px and persisted to localStorage through the existing guarded safeStorage wrapper, so it survives reloads and degrades to the default in private-mode / SSR contexts.
Double-clicking the handle resets the width to the 380px default.
motion/react drives the slide-in / slide-out, matching the existing right-docked drawer idiom (slideInRight), wrapped in AnimatePresence so the exit animation plays on close.

#6155 — larger, manually-growable prompt editor

The prompt <textarea> gets a taller default (min-h-32) and is now vertically resizable (resize-y) up to a 28rem cap, with relaxed line height; the wider docked panel also gives it real horizontal room.
The previously hardcoded English Prompt label and its ({{input}} = prev output) hint are moved to i18n.

i18n

New keys canvas.resize_panel, canvas.prompt_label, canvas.prompt_input_hint added to all three locale files (en.json, zh.json, uk.json).
The prompt_input_hint value keeps the literal {{input}} placeholder, mirroring the existing canvas.output_var_hint pattern (i18next leaves it unreplaced when no interpolation value is supplied).

Behavior preserved

All existing NodeConfigPanel functionality is untouched: agent binding, prompt, execution mode (sequential / fan-out / collect / conditional / loop), conditional / loop / retry fields, timeout, output variable, depends_on multi-select, save, and delete.
The panel is still hidden while the run-input dialog is open (same !showRunInput guard), and node selection / deletion still opens / closes it the same way.

Verification

• pnpm typecheck — 0 errors.
• pnpm lint — 0 errors; CanvasPage warning count unchanged at 9 (all pre-existing, in untouched code).
• pnpm test — 794 passed (80 files).
• pnpm build — succeeds (the >500kB chunk warning is pre-existing and unrelated).
• pnpm test:i18n-parity — en / zh / uk in parity.

No CanvasPage.test.tsx exists, so no editor test needed updating; WorkflowsPage.test.tsx is unaffected and stays green.

Maintainer notes

• Width band: min 300px, max 720px, default 380px (AGENT_PANEL_MIN/MAX/DEFAULT_WIDTH in CanvasPage.tsx). localStorage key is canvas.agentPanelWidth.
• On phones (< sm) the panel spans the full canvas row and the resize handle is hidden — there is no room to dock a fixed column and drag-resize it on a narrow screen. The panel still renders and is fully usable on mobile, it just isn't resizable there.
• The .secrets.baseline change is mechanical line-number churn from the pre-commit detect-secrets hook (the three new i18n keys pushed existing false-positive "Secret Keyword" label entries in en.json down by three lines); no new flagged entries were introduced.

Closes #6154
Closes #6155