Harden stats APIs and fix Electron Yomitan debug runtime

- Validate stats session IDs/limits and add AnkiConnect request timeouts
- Stabilize stats window/runtime lifecycle and tighten window security defaults
- Fix Electron CLI debug startup by unsetting `ELECTRON_RUN_AS_NODE` and wiring Yomitan session state
- Expand regression coverage for tracker queries/events ordering and session aggregates
- Update docs for stats dashboard usage and Yomitan lookup troubleshooting

backlog/tasks/task-174 - Fix-missing-frequency-highlights-for-merged-tokenizer-tokens.md

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+---
+id: TASK-174
+title: Fix missing frequency highlights for merged tokenizer tokens
+status: In Progress
+assignee:
+  - codex
+created_date: '2026-03-15 10:18'
+updated_date: '2026-03-15 10:40'
+labels:
+  - bug
+  - tokenizer
+  - frequency-highlighting
+dependencies: []
+references:
+  - /Users/sudacode/projects/japanese/SubMiner/src/core/services/tokenizer.ts
+  - >-
+    /Users/sudacode/projects/japanese/SubMiner/src/core/services/tokenizer/parser-selection-stage.ts
+  - >-
+    /Users/sudacode/projects/japanese/SubMiner/src/core/services/tokenizer/yomitan-parser-runtime.ts
+  - /Users/sudacode/projects/japanese/SubMiner/scripts/get_frequency.ts
+  - /Users/sudacode/projects/japanese/SubMiner/scripts/test-yomitan-parser.ts
+priority: high
+---
+
+## Description
+
+<!-- SECTION:DESCRIPTION:BEGIN -->
+Frequency highlighting can miss words that should color within the configured top-X limit when tokenizer candidate selection keeps merged Yomitan units that combine a content word with trailing function text. The annotation stage then conservatively clears frequency for the whole merged token, so visible high-frequency words lose highlighting. The standalone debug CLIs are also failing to initialize the shared Yomitan runtime, which blocks reliable repro for this class of bug.
+<!-- SECTION:DESCRIPTION:END -->
+
+## Acceptance Criteria
+<!-- AC:BEGIN -->
+- [ ] #1 Tokenizer no longer drops frequency highlighting for content words in merged-token cases where a better scanning parse candidate would preserve highlightable tokens.
+- [ ] #2 A regression test covers the reported sentence shape and fails before the fix.
+- [ ] #3 The standalone frequency/parser debug path can initialize the shared Yomitan runtime well enough to reproduce tokenizer output instead of immediately reporting runtime/session wiring errors.
+<!-- AC:END -->
+
+## Implementation Plan
+
+<!-- SECTION:PLAN:BEGIN -->
+1. Add a regression test for the reported merged-token frequency miss, centered on Yomitan scanning candidate selection and downstream frequency annotation.
+2. Update tokenizer candidate selection so merged content+function tokens do not win over candidates that preserve highlightable content tokens.
+3. Repair the standalone frequency/parser debug scripts so their Electron/Yomitan runtime wiring matches current shared runtime expectations.
+4. Verify with targeted tokenizer/parser tests and the standalone debug repro command.
+<!-- SECTION:PLAN:END -->
+
+## Implementation Notes
+
+<!-- SECTION:NOTES:BEGIN -->
+Initial triage: shared frequency class logic looks correct; likely failure is upstream tokenizer candidate selection producing merged content+function tokens that annotation later excludes from frequency. Standalone debug scripts also fail to initialize a usable Electron/Yomitan runtime, blocking reliable repro from the current CLI path.
+
+Repro after fixing the standalone Electron wrapper does not support the original highlight claim for `誰でもいいから かかってこいよ`: the tokenizer reports `かかってこい` with `frequencyRank` 63098, so it correctly stays uncolored at `--color-top-x 10000` and becomes colorable once the threshold is raised above that rank. The concrete bug fixed in this pass is the standalone Electron debug path: package scripts now unset `ELECTRON_RUN_AS_NODE`, and the scripts normalize Electron imports/guards so `get-frequency:electron` can reach real Electron/Yomitan runtime state instead of immediately falling back to Node-mode diagnostics. `test-yomitan-parser:electron` still shows extension/service-worker issues against the existing profile and was not stabilized in this pass.
+<!-- SECTION:NOTES:END -->

backlog/tasks/task-175 - Address-latest-PR-19-review-comments.md

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+---
+id: TASK-175
+title: Address latest PR 19 review comments
+status: In Progress
+assignee: []
+created_date: '2026-03-15 10:25'
+labels:
+  - pr-review
+  - stats-dashboard
+dependencies: []
+references:
+  - src/core/services/ipc.ts
+  - src/core/services/stats-server.ts
+  - src/core/services/immersion-tracker/__tests__/query.test.ts
+  - src/core/services/stats-window-runtime.ts
+  - src/core/services/stats-window.test.ts
+  - src/shared/ipc/contracts.ts
+  - src/main.ts
+priority: medium
+---
+
+## Description
+
+<!-- SECTION:DESCRIPTION:BEGIN -->
+Validate the latest automated review comments on PR #19 against the current branch, implement the technically valid fixes, and document any items intentionally left unchanged.
+<!-- SECTION:DESCRIPTION:END -->
+
+## Acceptance Criteria
+<!-- AC:BEGIN -->
+- [ ] #1 Validated the latest PR #19 review comments against current branch behavior and existing architecture
+- [ ] #2 Implemented the accepted fixes with regression coverage where it fits
+- [ ] #3 Documented which latest review items were intentionally not changed because they were already addressed or not technically warranted
+<!-- AC:END -->