feat: add token summaries and date filters

- add per-session and filtered-session token usage summaries with copy support
- scan token counts efficiently across filtered Codex session logs
- apply Codex folder-date filters through backend session discovery
- document token summary UI and bump app version to 1.3.0

ci: configure dependabot for Bun and actions

Replace the unused NuGet Dependabot update block with ecosystems that match this repository.

Add weekly Bun dependency updates for package.json and bun.lock, and add weekly GitHub Actions updates for workflow action pins.

This app does not contain NuGet or .NET package manifests, so the previous NuGet configuration could not produce useful dependency update PRs.

Verified with:
- bun run build

Add session browser dialog and bump 1.2.0

Introduce a full-window session browser dialog in the desktop app with transcript loading, search, copy actions, tool call filtering, and large-session safeguards.

Add transcript RPC/backend support to read session entries without executing anything and surface truncation plus oversized-row metadata to the UI.

Refresh README CLI/docs details and bump the app version to 1.2.0 while updating Bun references to 1.3.12 in package metadata and GitHub workflows.

feat: re-add sanitized sessions as canonical Codex rollouts

Add a sanitize modal option to re-add a sanitized copy into today's Codex sessions/YYYY/MM/DD folder using the canonical rollout naming scheme.

Introduce shared rollout helpers for Codex timestamp formatting, UUIDv7 thread ID generation, and current-day rollout path creation.
Reuse one fresh thread ID consistently across the rewritten rollout filename, session_meta.id, and sanitization report.

Wire the sanitize RPC and Bun backend to accept codexHome plus the re-add option, while keeping the existing temp-folder sanitized copy/report flow intact. Also avoid double-counting sanitization stats when both output targets are written in one run.

feat: improve export UX and session metrics