Add interactive mrun monitor improvements

[svadapalli1994]

Summary

• Adds and hardens the interactive mrun --monitor experience for local MongoDB deployments.
• Keeps the implementation spec in doc/feature-monitor-guide.md as the reviewer-facing architecture and behavior guide.
• Updates user-facing docs and CLI help so controls match the final monitor behavior.

Development history

• Added the top-level mrun --monitor path and kept it separate from normal command dispatch.
• Added mrun-managed process discovery from .mrun_startup.
• Added --monitor --all and in-dashboard scope toggling for all local mongod and mongos processes.
• Added auth and TLS metadata loading from startup data.
• Added explicit monitor credential overrides for sampling and shell handoff.
• Added CPU, memory, network, disk, and log monitor panes.
• Added pane focus, full-pane zoom, and cached redraws for cursor-only actions.
• Added direct tty escape-sequence parsing so arrow keys work reliably.
• Added CPU process selection, raw/normalized CPU display, and optional thread view.
• Added thread-count fallback when detailed thread timing is denied.
• Added MongoDB role detection from serverStatus(), with hello and isMaster fallbacks.
• Added role columns across CPU, memory, network, disk, and currentOp rows.
• Added the two-column layout with a left metric stack and right-side log/currentOp activity pane.
• Added strict log selection by visible index or displayed port, with invalid-input re-prompts.
• Added external-process handling so logs for non-mrun processes require an explicit user-provided path.
• Added bounded log tailing, recent-file seeding, timestamp merge ordering, pause/resume, and stable cursor/viewport behavior.
• Added log severity coloring, selected/yanked row priority handling, OSC 52 copy support, and syntax-colored Pretty JSON.
• Added local fuzzy and structured log filtering for slow operations, commands, components, severity, ports, and messages.
• Added on-demand top-N currentOp sampling in the log activity pane.
• Added formatted and raw BSON-safe currentOp display modes.
• Added currentOp namespace filtering, active namespace selection, Pretty JSON, yank support, source-node selection, and pause/resume.
• Added currentOp command compatibility fallbacks for supported MongoDB versions that reject optional fields.
• Added M key mongosh handoff with primary, selected-node, seed-list, first-node, and custom-URI targets.
• Added secure mongosh argv construction that reuses monitor auth/TLS options without exposing password values in argv.
• Added expanded serverStatus() mode with Disk, Network, Storage, and Other Subsystems panels.
• Added raw serverStatus() retention for inspectable promoted subsystem panes.
• Added selectable undisplayed subsystem browsing, Enter-to-promote behavior, round-robin promotion targets, and r reset.
• Added rate warm-up labels before a previous counter sample exists.
• Added rate-window display after a baseline exists.
• Added counter-reset clamping so derived rates do not go negative.
• Added ANSI-aware rendering primitives: neutral borders, pane-colored bold titles and table headers, aligned tables, stable left padding, and clipped footers.
• Added focused tests for monitor CLI routing, sampling, rendering, prompts, key handling, currentOp behavior, expanded status behavior, log filtering, and failure/status messages.
• Cleaned generated development artifacts out of the branch; Graphify/helper output was moved to /tmp/mongorun-side-scripts, and local runtime data/ was deleted.

Implementation spec

• doc/feature-monitor-guide.md documents the final monitor architecture, runtime flows, keyboard controls, data models, failure behavior, test coverage, and manual review checklist.
• The guide was cleaned to match this PR's scope and no longer documents moved helper scripts as part of the feature.

Files changed

• mrun/monitor.py
• mrun/mrun.py
• mrun/test/test_monitor.py
• doc/feature-monitor-guide.md
• doc/monitor.md
• doc/mrun.rst

Validation

• uv run --isolated --python python3.11 --no-python-downloads --with-requirements requirements.txt --with-requirements test-requirements.txt pytest mrun/test/test_monitor.py
• git diff --check