[Bugfix #1180] Raise per-window terminal cap + expose as codev.maxTerminals (default 25)

[amrmelsayed]

Summary

The VS Code extension capped concurrent terminals at 10 via a static MAX_TERMINALS = 10 constant. In multi-architect workspaces this is impractical: main + sibling architects consume several slots before any builder terminal opens, and architect terminals are the least-closeable type (closing one loses AI conversation state until the next reconciliation).

This exposes the cap as a codev.maxTerminals setting (default 25, min 5, max 100) so users can tune it. 25 accommodates ~10 architects + ~20 builders, well above realistic demand and comfortably below Tower's own maxSessions: 100 server-side backstop.

Root Cause

Static constant MAX_TERMINALS = 10 at packages/vscode/src/terminal-manager.ts:10, enforced in openTerminal (:465), with no configuration surface. The cap dates from Spec 0602 (single-architect era); sibling architects arrived later (Spec 755/786) but the cap was never re-scoped. The client-side 10 was the binding constraint — Tower already backstops at 100.

Fix

• terminal-manager.ts: replace MAX_TERMINALS = 10 with DEFAULT_MAX_TERMINALS = 25; openTerminal reads codev.maxTerminals via the config getter (falling back to the default). The over-cap toast now reads Too many terminals (N max) — close unused terminals or raise codev.maxTerminals so users know the knob exists. Two doc-comment references updated to codev.maxTerminals.
• package.json: new codev.maxTerminals number setting (default 25, min 5, max 100) with a markdownDescription explaining the memory-vs-capacity trade-off.

Net diff: ~67 lines across 3 files. No change to Tower's server-side cap (out of scope).

Test Plan

• Added #1180 source-level guards in terminal-manager.test.ts (matching the file's existing source-guard harness, since a full TerminalManager needs heavy vscode mocking): verify the setting is read via getConfiguration('codev').get<number>('maxTerminals', DEFAULT_MAX_TERMINALS), that enforcement uses the configured value (not a hardcoded 10), that the toast points at the setting, and that the pre-vscode: raise per-window terminal cap + expose as codev.maxTerminals setting (default 25, up from 10) #1180 constant is gone.
• Added a package.json schema assertion for the new setting's default/min/max.
• Full vscode vitest suite green: 632 tests / 53 files pass. check-types clean. Porch build + test checks pass.

Fixes #1180

[amrmelsayed]

CMAP review (3-way, --type pr)

Model	Verdict	Confidence
gemini	APPROVE	HIGH
codex	COMMENT	HIGH
claude	APPROVE	HIGH

No REQUEST_CHANGES. One non-blocking nit from codex: the DEFAULT_MAX_TERMINALS code comment previously sized the default via "~10 architects + ~20 builders" (=30), which didn't add up to the default of 25. Addressed in eef5e9d8 by rewording the rationale qualitatively (no misleading arithmetic). Implementation itself was flagged as correct by all three.